diff --git a/core/build.gradle.kts b/core/build.gradle.kts
index 6d26a515..4457d108 100644
--- a/core/build.gradle.kts
+++ b/core/build.gradle.kts
@@ -2,6 +2,7 @@ plugins {
     kotlin("multiplatform")
 }
 
+val coroutinesVersion: String by project.ext
 val kotlinLoggingVersion: String by project.extra
 
 kotlin {
@@ -14,6 +15,7 @@ kotlin {
     sourceSets {
         commonMain {
             dependencies {
+                api("org.jetbrains.kotlinx:kotlinx-coroutines-core:$coroutinesVersion")
                 api("io.github.microutils:kotlin-logging:$kotlinLoggingVersion")
             }
         }
diff --git a/core/src/commonMain/kotlin/world/phantasmal/core/disposable/DisposableSupervisedScope.kt b/core/src/commonMain/kotlin/world/phantasmal/core/disposable/DisposableSupervisedScope.kt
new file mode 100644
index 00000000..5747bf18
--- /dev/null
+++ b/core/src/commonMain/kotlin/world/phantasmal/core/disposable/DisposableSupervisedScope.kt
@@ -0,0 +1,17 @@
+package world.phantasmal.core.disposable
+
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.SupervisorJob
+import kotlinx.coroutines.cancel
+import kotlin.coroutines.CoroutineContext
+import kotlin.reflect.KClass
+
+class DisposableSupervisedScope(
+    private val kClass: KClass<*>,
+    context: CoroutineContext,
+) : TrackedDisposable(), CoroutineScope by CoroutineScope(SupervisorJob() + context) {
+    override fun internalDispose() {
+        cancel("${kClass.simpleName} disposed.")
+        super.internalDispose()
+    }
+}
diff --git a/lib/build.gradle.kts b/lib/build.gradle.kts
index ba344dd3..70cbc83a 100644
--- a/lib/build.gradle.kts
+++ b/lib/build.gradle.kts
@@ -103,7 +103,7 @@ val generateOpcodes = tasks.register("generateOpcodes") {
 fun opcodeToCode(writer: PrintWriter, opcode: Map<String, Any>) {
     val code = (opcode["code"] as String).drop(2).toInt(16)
     val codeStr = code.toString(16).toUpperCase().padStart(2, '0')
-    val mnemonic = opcode["mnemonic"] as String? ?: "unknown_$codeStr"
+    val mnemonic = opcode["mnemonic"] as String? ?: "unknown_${codeStr.toLowerCase()}"
     val description = opcode["description"] as String?
     val stack = opcode["stack"] as String?
 
diff --git a/observable/src/commonMain/kotlin/world/phantasmal/observable/ObservableCreation.kt b/observable/src/commonMain/kotlin/world/phantasmal/observable/ObservableCreation.kt
new file mode 100644
index 00000000..c9519a2a
--- /dev/null
+++ b/observable/src/commonMain/kotlin/world/phantasmal/observable/ObservableCreation.kt
@@ -0,0 +1,3 @@
+package world.phantasmal.observable
+
+fun <T> emitter(): Emitter<T> = SimpleEmitter()
diff --git a/web/build.gradle.kts b/web/build.gradle.kts
index f967f501..ccb5adae 100644
--- a/web/build.gradle.kts
+++ b/web/build.gradle.kts
@@ -42,11 +42,11 @@ dependencies {
     implementation("org.jetbrains.kotlin:kotlin-serialization:$serializationVersion")
     implementation("org.jetbrains.kotlinx:kotlinx-datetime:0.1.1")
     implementation(npm("golden-layout", "^1.5.9"))
-    implementation(npm("monaco-editor", "^0.21.2"))
+    implementation(npm("monaco-editor", "0.20.0"))
     implementation(npm("three", "^0.122.0"))
 
     implementation(devNpm("file-loader", "^6.0.0"))
-    implementation(devNpm("monaco-editor-webpack-plugin", "^2.0.0"))
+    implementation(devNpm("monaco-editor-webpack-plugin", "1.9.0"))
 
     testImplementation(kotlin("test-js"))
     testImplementation(project(":test-utils"))
diff --git a/web/src/main/kotlin/world/phantasmal/web/application/widgets/NavigationWidget.kt b/web/src/main/kotlin/world/phantasmal/web/application/widgets/NavigationWidget.kt
index 1e59dd7b..c3f3a86c 100644
--- a/web/src/main/kotlin/world/phantasmal/web/application/widgets/NavigationWidget.kt
+++ b/web/src/main/kotlin/world/phantasmal/web/application/widgets/NavigationWidget.kt
@@ -2,6 +2,7 @@ package world.phantasmal.web.application.widgets
 
 import org.w3c.dom.Node
 import world.phantasmal.observable.value.falseVal
+import world.phantasmal.observable.value.list.listVal
 import world.phantasmal.observable.value.value
 import world.phantasmal.web.application.controllers.NavigationController
 import world.phantasmal.web.core.dom.externalLink
@@ -30,8 +31,8 @@ class NavigationWidget(private val ctrl: NavigationController) : Widget() {
                 val serverSelect = Select(
                     enabled = falseVal(),
                     label = "Server:",
-                    items = listOf("Ephinea"),
-                    selected = "Ephinea",
+                    items = listVal("Ephinea"),
+                    selected = value("Ephinea"),
                     tooltip = value("Only Ephinea is supported at the moment"),
                 )
                 addWidget(serverSelect.label!!)
diff --git a/web/src/main/kotlin/world/phantasmal/web/core/rendering/conversion/NinjaGeometryConversion.kt b/web/src/main/kotlin/world/phantasmal/web/core/rendering/conversion/NinjaGeometryConversion.kt
index 5f058ffc..378c3a87 100644
--- a/web/src/main/kotlin/world/phantasmal/web/core/rendering/conversion/NinjaGeometryConversion.kt
+++ b/web/src/main/kotlin/world/phantasmal/web/core/rendering/conversion/NinjaGeometryConversion.kt
@@ -19,9 +19,11 @@ private val NO_SCALE = Vector3(1.0, 1.0, 1.0)
 fun ninjaObjectToMesh(
     ninjaObject: NinjaObject<*>,
     textures: List<XvrTexture>,
-    boundingVolumes: Boolean = false
+    defaultMaterial: Material? = null,
+    boundingVolumes: Boolean = false,
 ): Mesh {
     val builder = MeshBuilder()
+    defaultMaterial?.let { builder.defaultMaterial(defaultMaterial) }
     builder.textures(textures)
     NinjaToMeshConverter(builder).convert(ninjaObject)
     return builder.buildMesh(boundingVolumes)
@@ -31,9 +33,11 @@ fun ninjaObjectToInstancedMesh(
     ninjaObject: NinjaObject<*>,
     textures: List<XvrTexture>,
     maxInstances: Int,
+    defaultMaterial: Material? = null,
     boundingVolumes: Boolean = false,
 ): InstancedMesh {
     val builder = MeshBuilder()
+    defaultMaterial?.let { builder.defaultMaterial(defaultMaterial) }
     builder.textures(textures)
     NinjaToMeshConverter(builder).convert(ninjaObject)
     return builder.buildInstancedMesh(maxInstances, boundingVolumes)
diff --git a/web/src/main/kotlin/world/phantasmal/web/core/stores/UiStore.kt b/web/src/main/kotlin/world/phantasmal/web/core/stores/UiStore.kt
index d93b10a7..6db7a46f 100644
--- a/web/src/main/kotlin/world/phantasmal/web/core/stores/UiStore.kt
+++ b/web/src/main/kotlin/world/phantasmal/web/core/stores/UiStore.kt
@@ -1,7 +1,10 @@
 package world.phantasmal.web.core.stores
 
 import kotlinx.browser.window
+import kotlinx.coroutines.launch
 import org.w3c.dom.events.KeyboardEvent
+import world.phantasmal.core.disposable.Disposable
+import world.phantasmal.core.disposable.disposable
 import world.phantasmal.observable.value.MutableVal
 import world.phantasmal.observable.value.Val
 import world.phantasmal.observable.value.eq
@@ -30,7 +33,7 @@ class UiStore(private val applicationUrl: ApplicationUrl) : Store() {
      * parameter values per [applicationUrl].
      */
     private val parameters: MutableMap<String, Map<String, String>> = mutableMapOf()
-    private val globalKeydownHandlers: MutableMap<String, (e: KeyboardEvent) -> Unit> =
+    private val globalKeyDownHandlers: MutableMap<String, suspend (e: KeyboardEvent) -> Unit> =
         mutableMapOf()
 
     /**
@@ -78,7 +81,7 @@ class UiStore(private val applicationUrl: ApplicationUrl) : Store() {
             .toMap()
 
         addDisposables(
-            window.disposableListener("keydown", ::dispatchGlobalKeydown),
+            window.disposableListener("keydown", ::dispatchGlobalKeyDown),
         )
 
         observe(applicationUrl.url) { setDataFromUrl(it) }
@@ -101,6 +104,21 @@ class UiStore(private val applicationUrl: ApplicationUrl) : Store() {
         }
     }
 
+    fun onGlobalKeyDown(
+        tool: PwToolType,
+        binding: String,
+        handler: suspend (KeyboardEvent) -> Unit,
+    ): Disposable {
+        val key = handlerKey(tool, binding)
+        require(key !in globalKeyDownHandlers) {
+            """Binding "$binding" already exists for tool $tool."""
+        }
+
+        globalKeyDownHandlers[key] = handler
+
+        return disposable { globalKeyDownHandlers.remove(key) }
+    }
+
     /**
      * Sets [currentTool], [path], [parameters] and [features].
      */
@@ -169,7 +187,7 @@ class UiStore(private val applicationUrl: ApplicationUrl) : Store() {
         }
     }
 
-    private fun dispatchGlobalKeydown(e: KeyboardEvent) {
+    private fun dispatchGlobalKeyDown(e: KeyboardEvent) {
         val bindingParts = mutableListOf<String>()
 
         if (e.ctrlKey) bindingParts.add("Ctrl")
@@ -179,11 +197,11 @@ class UiStore(private val applicationUrl: ApplicationUrl) : Store() {
 
         val binding = bindingParts.joinToString("-")
 
-        val handler = globalKeydownHandlers[handlerKey(currentTool.value, binding)]
+        val handler = globalKeyDownHandlers[handlerKey(currentTool.value, binding)]
 
         if (handler != null) {
             e.preventDefault()
-            handler(e)
+            scope.launch { handler(e) }
         }
     }
 
diff --git a/web/src/main/kotlin/world/phantasmal/web/core/undo/SimpleUndo.kt b/web/src/main/kotlin/world/phantasmal/web/core/undo/SimpleUndo.kt
new file mode 100644
index 00000000..acbfe60b
--- /dev/null
+++ b/web/src/main/kotlin/world/phantasmal/web/core/undo/SimpleUndo.kt
@@ -0,0 +1,57 @@
+package world.phantasmal.web.core.undo
+
+import world.phantasmal.observable.value.*
+import world.phantasmal.web.core.actions.Action
+
+/**
+ * Simply contains a single action. [canUndo] and [canRedo] must be managed manually.
+ */
+class SimpleUndo(
+    undoManager: UndoManager,
+    private val description: String,
+    undo: () -> Unit,
+    redo: () -> Unit,
+) : Undo {
+    private val action = object : Action {
+        override val description: String = this@SimpleUndo.description
+
+        override fun execute() {
+            redo()
+        }
+
+        override fun undo() {
+            undo()
+        }
+    }
+
+    override val canUndo: MutableVal<Boolean> = mutableVal(false)
+    override val canRedo: MutableVal<Boolean> = mutableVal(false)
+
+    override val firstUndo: Val<Action?> = canUndo.map { if (it) action else null }
+    override val firstRedo: Val<Action?> = canRedo.map { if (it) action else null }
+
+    init {
+        undoManager.addUndo(this)
+    }
+
+    override fun undo(): Boolean =
+        if (canUndo.value) {
+            action.undo()
+            true
+        } else {
+            false
+        }
+
+    override fun redo(): Boolean =
+        if (canRedo.value) {
+            action.execute()
+            true
+        } else {
+            false
+        }
+
+    override fun reset() {
+        canUndo.value = false
+        canRedo.value = false
+    }
+}
diff --git a/web/src/main/kotlin/world/phantasmal/web/core/undo/Undo.kt b/web/src/main/kotlin/world/phantasmal/web/core/undo/Undo.kt
index 9e2709a7..166f35da 100644
--- a/web/src/main/kotlin/world/phantasmal/web/core/undo/Undo.kt
+++ b/web/src/main/kotlin/world/phantasmal/web/core/undo/Undo.kt
@@ -17,10 +17,6 @@ interface Undo {
      */
     val firstRedo: Val<Action?>
 
-    /**
-     * Ensures this undo is the current undo in its [UndoManager].
-     */
-    fun makeCurrent()
     fun undo(): Boolean
     fun redo(): Boolean
     fun reset()
diff --git a/web/src/main/kotlin/world/phantasmal/web/core/undo/UndoManager.kt b/web/src/main/kotlin/world/phantasmal/web/core/undo/UndoManager.kt
index 5c6cade2..429aa93b 100644
--- a/web/src/main/kotlin/world/phantasmal/web/core/undo/UndoManager.kt
+++ b/web/src/main/kotlin/world/phantasmal/web/core/undo/UndoManager.kt
@@ -7,6 +7,7 @@ import world.phantasmal.observable.value.nullVal
 import world.phantasmal.web.core.actions.Action
 
 class UndoManager {
+    private val undos = mutableListOf<Undo>()
     private val _current = mutableVal<Undo>(NopUndo)
 
     val current: Val<Undo> = _current
@@ -16,7 +17,13 @@ class UndoManager {
     val firstUndo: Val<Action?> = current.flatMap { it.firstUndo }
     val firstRedo: Val<Action?> = current.flatMap { it.firstRedo }
 
+    fun addUndo(undo: Undo) {
+        undos.add(undo)
+    }
+
     fun setCurrent(undo: Undo) {
+        require(undo in undos) { "Undo $undo is not managed by this UndoManager." }
+
         _current.value = undo
     }
 
@@ -26,8 +33,11 @@ class UndoManager {
     fun redo(): Boolean =
         current.value.redo()
 
-    fun makeNopCurrent() {
-        setCurrent(NopUndo)
+    /**
+     * Resets all managed undos.
+     */
+    fun reset() {
+        undos.forEach { it.reset() }
     }
 
     private object NopUndo : Undo {
@@ -36,10 +46,6 @@ class UndoManager {
         override val firstUndo = nullVal()
         override val firstRedo = nullVal()
 
-        override fun makeCurrent() {
-            // Do nothing.
-        }
-
         override fun undo(): Boolean = false
 
         override fun redo(): Boolean = false
diff --git a/web/src/main/kotlin/world/phantasmal/web/core/undo/UndoStack.kt b/web/src/main/kotlin/world/phantasmal/web/core/undo/UndoStack.kt
index 02b66ba9..1911e16f 100644
--- a/web/src/main/kotlin/world/phantasmal/web/core/undo/UndoStack.kt
+++ b/web/src/main/kotlin/world/phantasmal/web/core/undo/UndoStack.kt
@@ -10,7 +10,7 @@ import world.phantasmal.web.core.actions.Action
 /**
  * Full-fledged linear undo/redo implementation.
  */
-class UndoStack(private val manager: UndoManager) : Undo {
+class UndoStack(manager: UndoManager) : Undo {
     private val stack = mutableListVal<Action>()
 
     /**
@@ -20,6 +20,10 @@ class UndoStack(private val manager: UndoManager) : Undo {
     private val index = mutableVal(0)
     private var undoingOrRedoing = false
 
+    init {
+        manager.addUndo(this)
+    }
+
     override val canUndo: Val<Boolean> = index gt 0
 
     override val canRedo: Val<Boolean> = map(stack, index) { stack, index -> index < stack.size }
@@ -28,10 +32,6 @@ class UndoStack(private val manager: UndoManager) : Undo {
 
     override val firstRedo: Val<Action?> = index.map { stack.value.getOrNull(it) }
 
-    override fun makeCurrent() {
-        manager.setCurrent(this)
-    }
-
     fun push(action: Action): Action {
         if (!undoingOrRedoing) {
             stack.splice(index.value, stack.value.size - index.value, action)
diff --git a/web/src/main/kotlin/world/phantasmal/web/externals/monacoEditor/editor.kt b/web/src/main/kotlin/world/phantasmal/web/externals/monacoEditor/editor.kt
index 833cd8fc..685c8959 100644
--- a/web/src/main/kotlin/world/phantasmal/web/externals/monacoEditor/editor.kt
+++ b/web/src/main/kotlin/world/phantasmal/web/externals/monacoEditor/editor.kt
@@ -7,6 +7,7 @@ package world.phantasmal.web.externals.monacoEditor
 
 import org.w3c.dom.HTMLElement
 import org.w3c.dom.Range
+import kotlin.js.Promise
 
 external fun create(
     domElement: HTMLElement,
@@ -122,7 +123,7 @@ external interface IEditor {
         scrollType: ScrollType = definedExternally,
     )
 
-    fun trigger(source: String?, handlerId: String, payload: Any)
+    fun trigger(source: String?, handlerId: String, payload: dynamic)
     fun getModel(): dynamic /* ITextModel? | IDiffEditorModel? */
     fun setModel(model: ITextModel?)
 }
@@ -180,6 +181,26 @@ external interface ICodeEditor : IEditor {
     fun getOffsetForColumn(lineNumber: Number, column: Number): Number
     fun render(forceRedraw: Boolean = definedExternally)
     fun applyFontInfo(target: HTMLElement)
+    fun getSupportedActions(): Array<IEditorAction>
+    fun getAction(id: String): IEditorAction
+    fun addAction(descriptor: IActionDescriptor): IDisposable
+}
+
+external interface IActionDescriptor {
+    var id: String
+    var label: String
+    var keybindings: Array<Int>
+
+    fun run(editor: ICodeEditor, vararg args: dynamic): dynamic
+}
+
+external interface IEditorAction {
+    val id: String
+    val label: String
+    val alias: String
+
+    fun isSupported(): Boolean
+    fun run(): Promise<Unit>
 }
 
 external interface IStandaloneCodeEditor : ICodeEditor {
@@ -540,8 +561,8 @@ external interface ITextModel {
     var uri: Uri
     var id: String
     fun getOptions(): TextModelResolvedOptions
-    fun getVersionId(): Number
-    fun getAlternativeVersionId(): Number
+    fun getVersionId(): Int
+    fun getAlternativeVersionId(): Int
     fun setValue(newValue: String)
     fun getValue(
         eol: EndOfLinePreference = definedExternally,
diff --git a/web/src/main/kotlin/world/phantasmal/web/externals/monacoEditor/monacoEditor.kt b/web/src/main/kotlin/world/phantasmal/web/externals/monacoEditor/monacoEditor.kt
index bd19012d..d3db1503 100644
--- a/web/src/main/kotlin/world/phantasmal/web/externals/monacoEditor/monacoEditor.kt
+++ b/web/src/main/kotlin/world/phantasmal/web/externals/monacoEditor/monacoEditor.kt
@@ -181,3 +181,203 @@ open external class Uri : UriComponents {
         fun revive(data: Uri? = definedExternally): Uri?
     }
 }
+
+external object KeyCode {
+    /**
+     * Placed first to cover the 0 value of the enum.
+     */
+    val Unknown: Int /* = 0 */
+    val Backspace: Int /* = 1 */
+    val Tab: Int /* = 2 */
+    val Enter: Int /* = 3 */
+    val Shift: Int /* = 4 */
+    val Ctrl: Int /* = 5 */
+    val Alt: Int /* = 6 */
+    val PauseBreak: Int /* = 7 */
+    val CapsLock: Int /* = 8 */
+    val Escape: Int /* = 9 */
+    val Space: Int /* = 10 */
+    val PageUp: Int /* = 11 */
+    val PageDown: Int /* = 12 */
+    val End: Int /* = 13 */
+    val Home: Int /* = 14 */
+    val LeftArrow: Int /* = 15 */
+    val UpArrow: Int /* = 16 */
+    val RightArrow: Int /* = 17 */
+    val DownArrow: Int /* = 18 */
+    val Insert: Int /* = 19 */
+    val Delete: Int /* = 20 */
+    val KEY_0: Int /* = 21 */
+    val KEY_1: Int /* = 22 */
+    val KEY_2: Int /* = 23 */
+    val KEY_3: Int /* = 24 */
+    val KEY_4: Int /* = 25 */
+    val KEY_5: Int /* = 26 */
+    val KEY_6: Int /* = 27 */
+    val KEY_7: Int /* = 28 */
+    val KEY_8: Int /* = 29 */
+    val KEY_9: Int /* = 30 */
+    val KEY_A: Int /* = 31 */
+    val KEY_B: Int /* = 32 */
+    val KEY_C: Int /* = 33 */
+    val KEY_D: Int /* = 34 */
+    val KEY_E: Int /* = 35 */
+    val KEY_F: Int /* = 36 */
+    val KEY_G: Int /* = 37 */
+    val KEY_H: Int /* = 38 */
+    val KEY_I: Int /* = 39 */
+    val KEY_J: Int /* = 40 */
+    val KEY_K: Int /* = 41 */
+    val KEY_L: Int /* = 42 */
+    val KEY_M: Int /* = 43 */
+    val KEY_N: Int /* = 44 */
+    val KEY_O: Int /* = 45 */
+    val KEY_P: Int /* = 46 */
+    val KEY_Q: Int /* = 47 */
+    val KEY_R: Int /* = 48 */
+    val KEY_S: Int /* = 49 */
+    val KEY_T: Int /* = 50 */
+    val KEY_U: Int /* = 51 */
+    val KEY_V: Int /* = 52 */
+    val KEY_W: Int /* = 53 */
+    val KEY_X: Int /* = 54 */
+    val KEY_Y: Int /* = 55 */
+    val KEY_Z: Int /* = 56 */
+    val Meta: Int /* = 57 */
+    val ContextMenu: Int /* = 58 */
+    val F1: Int /* = 59 */
+    val F2: Int /* = 60 */
+    val F3: Int /* = 61 */
+    val F4: Int /* = 62 */
+    val F5: Int /* = 63 */
+    val F6: Int /* = 64 */
+    val F7: Int /* = 65 */
+    val F8: Int /* = 66 */
+    val F9: Int /* = 67 */
+    val F10: Int /* = 68 */
+    val F11: Int /* = 69 */
+    val F12: Int /* = 70 */
+    val F13: Int /* = 71 */
+    val F14: Int /* = 72 */
+    val F15: Int /* = 73 */
+    val F16: Int /* = 74 */
+    val F17: Int /* = 75 */
+    val F18: Int /* = 76 */
+    val F19: Int /* = 77 */
+    val NumLock: Int /* = 78 */
+    val ScrollLock: Int /* = 79 */
+
+    /**
+     * Used for miscellaneous characters; it can vary by keyboard.
+     * For the US standard keyboard, the ';:' key
+     */
+    val US_SEMICOLON: Int /* = 80 */
+
+    /**
+     * For any country/region, the '+' key
+     * For the US standard keyboard, the '=+' key
+     */
+    val US_EQUAL: Int /* = 81 */
+
+    /**
+     * For any country/region, the ',' key
+     * For the US standard keyboard, the ',<' key
+     */
+    val US_COMMA: Int /* = 82 */
+
+    /**
+     * For any country/region, the '-' key
+     * For the US standard keyboard, the '-_' key
+     */
+    val US_MINUS: Int /* = 83 */
+
+    /**
+     * For any country/region, the '.' key
+     * For the US standard keyboard, the '.>' key
+     */
+    val US_DOT: Int /* = 84 */
+
+    /**
+     * Used for miscellaneous characters; it can vary by keyboard.
+     * For the US standard keyboard, the '/?' key
+     */
+    val US_SLASH: Int /* = 85 */
+
+    /**
+     * Used for miscellaneous characters; it can vary by keyboard.
+     * For the US standard keyboard, the '`~' key
+     */
+    val US_BACKTICK: Int /* = 86 */
+
+    /**
+     * Used for miscellaneous characters; it can vary by keyboard.
+     * For the US standard keyboard, the '[{' key
+     */
+    val US_OPEN_SQUARE_BRACKET: Int /* = 87 */
+
+    /**
+     * Used for miscellaneous characters; it can vary by keyboard.
+     * For the US standard keyboard, the '\|' key
+     */
+    val US_BACKSLASH: Int /* = 88 */
+
+    /**
+     * Used for miscellaneous characters; it can vary by keyboard.
+     * For the US standard keyboard, the ']}' key
+     */
+    val US_CLOSE_SQUARE_BRACKET: Int /* = 89 */
+
+    /**
+     * Used for miscellaneous characters; it can vary by keyboard.
+     * For the US standard keyboard, the ''"' key
+     */
+    val US_QUOTE: Int /* = 90 */
+
+    /**
+     * Used for miscellaneous characters; it can vary by keyboard.
+     */
+    val OEM_8: Int /* = 91 */
+
+    /**
+     * Either the angle bracket key or the backslash key on the RT 102-key keyboard.
+     */
+    val OEM_102: Int /* = 92 */
+    val NUMPAD_0: Int /* = 93 */
+    val NUMPAD_1: Int /* = 94 */
+    val NUMPAD_2: Int /* = 95 */
+    val NUMPAD_3: Int /* = 96 */
+    val NUMPAD_4: Int /* = 97 */
+    val NUMPAD_5: Int /* = 98 */
+    val NUMPAD_6: Int /* = 99 */
+    val NUMPAD_7: Int /* = 100 */
+    val NUMPAD_8: Int /* = 101 */
+    val NUMPAD_9: Int /* = 102 */
+    val NUMPAD_MULTIPLY: Int /* = 103 */
+    val NUMPAD_ADD: Int /* = 104 */
+    val NUMPAD_SEPARATOR: Int /* = 105 */
+    val NUMPAD_SUBTRACT: Int /* = 106 */
+    val NUMPAD_DECIMAL: Int /* = 107 */
+    val NUMPAD_DIVIDE: Int /* = 108 */
+
+    /**
+     * Cover all key codes when IME is processing input.
+     */
+    val KEY_IN_COMPOSITION: Int /* = 109 */
+    val ABNT_C1: Int /* = 110 */
+    val ABNT_C2: Int /* = 111 */
+
+    /**
+     * Placed last to cover the length of the enum.
+     * Please do not depend on this value!
+     */
+    val MAX_VALUE: Int /* = 112 */
+}
+
+external object KeyMod {
+    val CtrlCmd: Int
+    val Shift: Int
+    val Alt: Int
+    val WinCtrl: Int
+
+    fun chord(firstPart: Int, secondPart: Int): Int
+}
diff --git a/web/src/main/kotlin/world/phantasmal/web/externals/three/three.kt b/web/src/main/kotlin/world/phantasmal/web/externals/three/three.kt
index 43856a28..a39d9ba1 100644
--- a/web/src/main/kotlin/world/phantasmal/web/externals/three/three.kt
+++ b/web/src/main/kotlin/world/phantasmal/web/externals/three/three.kt
@@ -535,7 +535,7 @@ external class CylinderBufferGeometry(
 open external class BufferAttribute {
     var needsUpdate: Boolean
 
-    fun copyAt(index1: Int, attribute: BufferAttribute, index2: Int): BufferAttribute
+    fun copyAt(index1: Int, bufferAttribute: BufferAttribute, index2: Int): BufferAttribute
 }
 
 external class Uint16BufferAttribute(
diff --git a/web/src/main/kotlin/world/phantasmal/web/questEditor/QuestEditor.kt b/web/src/main/kotlin/world/phantasmal/web/questEditor/QuestEditor.kt
index 78fd38e4..3b20d83a 100644
--- a/web/src/main/kotlin/world/phantasmal/web/questEditor/QuestEditor.kt
+++ b/web/src/main/kotlin/world/phantasmal/web/questEditor/QuestEditor.kt
@@ -6,6 +6,7 @@ import world.phantasmal.web.core.PwToolType
 import world.phantasmal.web.core.loading.AssetLoader
 import world.phantasmal.web.core.rendering.DisposableThreeRenderer
 import world.phantasmal.web.core.stores.UiStore
+import world.phantasmal.web.core.undo.UndoManager
 import world.phantasmal.web.questEditor.controllers.*
 import world.phantasmal.web.questEditor.loading.AreaAssetLoader
 import world.phantasmal.web.questEditor.loading.EntityAssetLoader
@@ -14,7 +15,7 @@ import world.phantasmal.web.questEditor.persistence.QuestEditorUiPersister
 import world.phantasmal.web.questEditor.rendering.EntityImageRenderer
 import world.phantasmal.web.questEditor.rendering.QuestRenderer
 import world.phantasmal.web.questEditor.stores.AreaStore
-import world.phantasmal.web.questEditor.stores.AssemblyEditorStore
+import world.phantasmal.web.questEditor.stores.AsmStore
 import world.phantasmal.web.questEditor.stores.QuestEditorStore
 import world.phantasmal.web.questEditor.widgets.*
 import world.phantasmal.webui.DisposableContainer
@@ -36,14 +37,22 @@ class QuestEditor(
         // Persistence
         val questEditorUiPersister = QuestEditorUiPersister()
 
+        // Undo
+        val undoManager = UndoManager()
+
         // Stores
         val areaStore = addDisposable(AreaStore(areaAssetLoader))
-        val questEditorStore = addDisposable(QuestEditorStore(uiStore, areaStore))
-        val assemblyEditorStore = addDisposable(AssemblyEditorStore(questEditorStore))
+        val questEditorStore = addDisposable(QuestEditorStore(
+            uiStore,
+            areaStore,
+            undoManager,
+        ))
+        val asmStore = addDisposable(AsmStore(questEditorStore, undoManager))
 
         // Controllers
         val questEditorController = addDisposable(QuestEditorController(questEditorUiPersister))
         val toolbarController = addDisposable(QuestEditorToolbarController(
+            uiStore,
             questLoader,
             areaStore,
             questEditorStore,
@@ -51,7 +60,7 @@ class QuestEditor(
         val questInfoController = addDisposable(QuestInfoController(questEditorStore))
         val npcCountsController = addDisposable(NpcCountsController(questEditorStore))
         val entityInfoController = addDisposable(EntityInfoController(questEditorStore))
-        val assemblyEditorController = addDisposable(AssemblyEditorController(assemblyEditorStore))
+        val asmController = addDisposable(AsmController(asmStore))
         val npcListController = addDisposable(EntityListController(questEditorStore, npcs = true))
         val objectListController =
             addDisposable(EntityListController(questEditorStore, npcs = false))
@@ -73,7 +82,7 @@ class QuestEditor(
             { NpcCountsWidget(npcCountsController) },
             { EntityInfoWidget(entityInfoController) },
             { QuestEditorRendererWidget(renderer) },
-            { AssemblyEditorWidget(assemblyEditorController) },
+            { AsmWidget(asmController) },
             { EntityListWidget(npcListController, entityImageRenderer) },
             { EntityListWidget(objectListController, entityImageRenderer) },
         )
diff --git a/web/src/main/kotlin/world/phantasmal/web/questEditor/actions/DeleteEntityAction.kt b/web/src/main/kotlin/world/phantasmal/web/questEditor/actions/DeleteEntityAction.kt
new file mode 100644
index 00000000..6cb63532
--- /dev/null
+++ b/web/src/main/kotlin/world/phantasmal/web/questEditor/actions/DeleteEntityAction.kt
@@ -0,0 +1,22 @@
+package world.phantasmal.web.questEditor.actions
+
+import world.phantasmal.web.core.actions.Action
+import world.phantasmal.web.questEditor.models.QuestEntityModel
+import world.phantasmal.web.questEditor.models.QuestModel
+
+class DeleteEntityAction(
+    private val setSelectedEntity: (QuestEntityModel<*, *>) -> Unit,
+    private val quest: QuestModel,
+    private val entity: QuestEntityModel<*, *>,
+) :Action{
+    override val description: String = "Delete ${entity.type.name}"
+
+    override fun execute() {
+        quest.removeEntity(entity)
+    }
+
+    override fun undo() {
+        quest.addEntity(entity)
+        setSelectedEntity(entity)
+    }
+}
diff --git a/web/src/main/kotlin/world/phantasmal/web/questEditor/assembly/AssemblyAnalyser.kt b/web/src/main/kotlin/world/phantasmal/web/questEditor/asm/AsmAnalyser.kt
similarity index 54%
rename from web/src/main/kotlin/world/phantasmal/web/questEditor/assembly/AssemblyAnalyser.kt
rename to web/src/main/kotlin/world/phantasmal/web/questEditor/asm/AsmAnalyser.kt
index a5f8749c..deaecb60 100644
--- a/web/src/main/kotlin/world/phantasmal/web/questEditor/assembly/AssemblyAnalyser.kt
+++ b/web/src/main/kotlin/world/phantasmal/web/questEditor/asm/AsmAnalyser.kt
@@ -1,8 +1,8 @@
-package world.phantasmal.web.questEditor.assembly
+package world.phantasmal.web.questEditor.asm
 
 import world.phantasmal.core.disposable.TrackedDisposable
 
-class AssemblyAnalyser : TrackedDisposable() {
+class AsmAnalyser : TrackedDisposable() {
     fun setAssembly(assembly: List<String>) {
     }
 }
diff --git a/web/src/main/kotlin/world/phantasmal/web/questEditor/controllers/AsmController.kt b/web/src/main/kotlin/world/phantasmal/web/questEditor/controllers/AsmController.kt
new file mode 100644
index 00000000..92d5ed77
--- /dev/null
+++ b/web/src/main/kotlin/world/phantasmal/web/questEditor/controllers/AsmController.kt
@@ -0,0 +1,38 @@
+package world.phantasmal.web.questEditor.controllers
+
+import world.phantasmal.observable.Observable
+import world.phantasmal.observable.value.*
+import world.phantasmal.web.externals.monacoEditor.ITextModel
+import world.phantasmal.web.externals.monacoEditor.createModel
+import world.phantasmal.web.questEditor.stores.AsmStore
+import world.phantasmal.webui.controllers.Controller
+
+class AsmController(private val store: AsmStore) : Controller() {
+    val enabled: Val<Boolean> = store.editingEnabled
+    val readOnly: Val<Boolean> = !enabled or store.textModel.isNull()
+
+    val textModel: Val<ITextModel> = store.textModel.orElse { EMPTY_MODEL }
+
+    val didUndo: Observable<Unit> = store.didUndo
+    val didRedo: Observable<Unit> = store.didRedo
+
+    val inlineStackArgs: Val<Boolean> = store.inlineStackArgs
+    val inlineStackArgsEnabled: Val<Boolean> = falseVal() // TODO
+
+    // TODO: Notify user when disabled because of issues with the ASM.
+    val inlineStackArgsTooltip: Val<String> = value(
+        "Transform arg_push* opcodes to be inline with the opcode the arguments are given to."
+    )
+
+    fun makeUndoCurrent() {
+        store.makeUndoCurrent()
+    }
+
+    fun setInlineStackArgs(value: Boolean) {
+        TODO()
+    }
+
+    companion object {
+        private val EMPTY_MODEL = createModel("", AsmStore.ASM_LANG_ID)
+    }
+}
diff --git a/web/src/main/kotlin/world/phantasmal/web/questEditor/controllers/AssemblyEditorController.kt b/web/src/main/kotlin/world/phantasmal/web/questEditor/controllers/AssemblyEditorController.kt
deleted file mode 100644
index de73165f..00000000
--- a/web/src/main/kotlin/world/phantasmal/web/questEditor/controllers/AssemblyEditorController.kt
+++ /dev/null
@@ -1,17 +0,0 @@
-package world.phantasmal.web.questEditor.controllers
-
-import world.phantasmal.observable.value.*
-import world.phantasmal.web.externals.monacoEditor.ITextModel
-import world.phantasmal.web.externals.monacoEditor.createModel
-import world.phantasmal.web.questEditor.stores.AssemblyEditorStore
-import world.phantasmal.webui.controllers.Controller
-
-class AssemblyEditorController(assemblyEditorStore: AssemblyEditorStore) : Controller() {
-    val textModel: Val<ITextModel> = assemblyEditorStore.textModel.orElse { EMPTY_MODEL }
-    val enabled: Val<Boolean> = assemblyEditorStore.editingEnabled
-    val readOnly: Val<Boolean> = enabled.not() or assemblyEditorStore.textModel.isNull()
-
-    companion object {
-        private val EMPTY_MODEL = createModel("", AssemblyEditorStore.ASM_LANG_ID)
-    }
-}
diff --git a/web/src/main/kotlin/world/phantasmal/web/questEditor/controllers/NpcCountsController.kt b/web/src/main/kotlin/world/phantasmal/web/questEditor/controllers/NpcCountsController.kt
index aa30edf2..933d88d4 100644
--- a/web/src/main/kotlin/world/phantasmal/web/questEditor/controllers/NpcCountsController.kt
+++ b/web/src/main/kotlin/world/phantasmal/web/questEditor/controllers/NpcCountsController.kt
@@ -7,13 +7,17 @@ import world.phantasmal.web.questEditor.models.QuestNpcModel
 import world.phantasmal.web.questEditor.stores.QuestEditorStore
 import world.phantasmal.webui.controllers.Controller
 
-class NpcCountsController(store: QuestEditorStore) : Controller() {
+class NpcCountsController(private val store: QuestEditorStore) : Controller() {
     val unavailable: Val<Boolean> = store.currentQuest.isNull()
 
     val npcCounts: Val<List<NameWithCount>> = store.currentQuest
         .flatMap { it?.npcs ?: emptyListVal() }
         .map(::countNpcs)
 
+    fun focused() {
+        store.makeMainUndoCurrent()
+    }
+
     private fun countNpcs(npcs: List<QuestNpcModel>): List<NameWithCount> {
         val npcCounts = mutableMapOf<NpcType, Int>()
         var extraCanadines = 0
diff --git a/web/src/main/kotlin/world/phantasmal/web/questEditor/controllers/QuestEditorController.kt b/web/src/main/kotlin/world/phantasmal/web/questEditor/controllers/QuestEditorController.kt
index 9e704485..9c2e7756 100644
--- a/web/src/main/kotlin/world/phantasmal/web/questEditor/controllers/QuestEditorController.kt
+++ b/web/src/main/kotlin/world/phantasmal/web/questEditor/controllers/QuestEditorController.kt
@@ -15,24 +15,24 @@ class QuestEditorController(
 
     companion object {
         // These IDs are persisted, don't change them.
-        const val QUEST_INFO_WIDGET_ID = "info"
-        const val NPC_COUNTS_WIDGET_ID = "npc_counts"
-        const val ENTITY_INFO_WIDGET_ID = "entity_info"
-        const val QUEST_RENDERER_WIDGET_ID = "quest_renderer"
-        const val ASSEMBLY_EDITOR_WIDGET_ID = "asm_editor"
-        const val NPC_LIST_WIDGET_ID = "npc_list_view"
-        const val OBJECT_LIST_WIDGET_ID = "object_list_view"
-        const val EVENTS_WIDGET_ID = "events_view"
+        const val QUEST_INFO_WIDGET_ID = "quest-info"
+        const val NPC_COUNTS_WIDGET_ID = "npc-counts"
+        const val ENTITY_INFO_WIDGET_ID = "entity-info"
+        const val QUEST_RENDERER_WIDGET_ID = "quest-renderer"
+        const val ASM_WIDGET_ID = "asm"
+        const val NPC_LIST_WIDGET_ID = "npc-list"
+        const val OBJECT_LIST_WIDGET_ID = "object-list"
+        const val EVENTS_WIDGET_ID = "events"
 
         private val ALL_WIDGET_IDS: Set<String> = setOf(
-            "info",
-            "npc_counts",
-            "entity_info",
-            "quest_renderer",
-            "asm_editor",
-            "npc_list_view",
-            "object_list_view",
-            "events_view",
+            QUEST_INFO_WIDGET_ID,
+            NPC_COUNTS_WIDGET_ID,
+            ENTITY_INFO_WIDGET_ID,
+            QUEST_RENDERER_WIDGET_ID,
+            ASM_WIDGET_ID,
+            NPC_LIST_WIDGET_ID,
+            OBJECT_LIST_WIDGET_ID,
+            EVENTS_WIDGET_ID,
         )
 
         private val DEFAULT_CONFIG = DockedRow(
@@ -67,7 +67,7 @@ class QuestEditorController(
                         ),
                         DockedWidget(
                             title = "Script",
-                            id = ASSEMBLY_EDITOR_WIDGET_ID,
+                            id = ASM_WIDGET_ID,
                         ),
                     )
                 ),
diff --git a/web/src/main/kotlin/world/phantasmal/web/questEditor/controllers/QuestEditorToolbarController.kt b/web/src/main/kotlin/world/phantasmal/web/questEditor/controllers/QuestEditorToolbarController.kt
index e99ab25c..0fb02cb0 100644
--- a/web/src/main/kotlin/world/phantasmal/web/questEditor/controllers/QuestEditorToolbarController.kt
+++ b/web/src/main/kotlin/world/phantasmal/web/questEditor/controllers/QuestEditorToolbarController.kt
@@ -13,6 +13,8 @@ import world.phantasmal.observable.value.Val
 import world.phantasmal.observable.value.map
 import world.phantasmal.observable.value.mutableVal
 import world.phantasmal.observable.value.value
+import world.phantasmal.web.core.PwToolType
+import world.phantasmal.web.core.stores.UiStore
 import world.phantasmal.web.questEditor.loading.QuestLoader
 import world.phantasmal.web.questEditor.models.AreaModel
 import world.phantasmal.web.questEditor.stores.AreaStore
@@ -20,12 +22,14 @@ import world.phantasmal.web.questEditor.stores.QuestEditorStore
 import world.phantasmal.web.questEditor.stores.convertQuestToModel
 import world.phantasmal.webui.controllers.Controller
 import world.phantasmal.webui.readFile
+import world.phantasmal.webui.selectFiles
 
 private val logger = KotlinLogging.logger {}
 
 class AreaAndLabel(val area: AreaModel, val label: String)
 
 class QuestEditorToolbarController(
+    uiStore: UiStore,
     private val questLoader: QuestLoader,
     private val areaStore: AreaStore,
     private val questEditorStore: QuestEditorStore,
@@ -38,6 +42,8 @@ class QuestEditorToolbarController(
     val resultDialogVisible: Val<Boolean> = _resultDialogVisible
     val result: Val<PwResult<*>?> = _result
 
+    val openFileAccept = ".bin, .dat, .qst"
+
     // Undo
 
     val undoTooltip: Val<String> = questEditorStore.firstUndo.map { action ->
@@ -75,6 +81,26 @@ class QuestEditorToolbarController(
 
     val areaSelectEnabled: Val<Boolean> = questEditorStore.currentQuest.isNotNull()
 
+    init {
+        addDisposables(
+            uiStore.onGlobalKeyDown(PwToolType.QuestEditor, "Ctrl-O") {
+                openFiles(selectFiles(accept = openFileAccept, multiple = true))
+            },
+
+            uiStore.onGlobalKeyDown(PwToolType.QuestEditor, "Ctrl-Z") {
+                undo()
+            },
+
+            uiStore.onGlobalKeyDown(PwToolType.QuestEditor, "Ctrl-Shift-Z") {
+                redo()
+            },
+
+            uiStore.onGlobalKeyDown(PwToolType.QuestEditor, "Ctrl-Y") {
+                redo()
+            },
+        )
+    }
+
     suspend fun createNewQuest(episode: Episode) {
         // TODO: Set filename and version.
         questEditorStore.setCurrentQuest(
diff --git a/web/src/main/kotlin/world/phantasmal/web/questEditor/loading/EntityAssetLoader.kt b/web/src/main/kotlin/world/phantasmal/web/questEditor/loading/EntityAssetLoader.kt
index 0b56d698..969c0068 100644
--- a/web/src/main/kotlin/world/phantasmal/web/questEditor/loading/EntityAssetLoader.kt
+++ b/web/src/main/kotlin/world/phantasmal/web/questEditor/loading/EntityAssetLoader.kt
@@ -14,10 +14,9 @@ import world.phantasmal.lib.fileFormats.quest.ObjectType
 import world.phantasmal.web.core.loading.AssetLoader
 import world.phantasmal.web.core.rendering.conversion.ninjaObjectToInstancedMesh
 import world.phantasmal.web.core.rendering.disposeObject3DResources
-import world.phantasmal.web.externals.three.CylinderBufferGeometry
-import world.phantasmal.web.externals.three.InstancedMesh
-import world.phantasmal.web.externals.three.MeshLambertMaterial
+import world.phantasmal.web.externals.three.*
 import world.phantasmal.webui.DisposableContainer
+import world.phantasmal.webui.obj
 
 private val logger = KotlinLogging.logger {}
 
@@ -26,10 +25,11 @@ class EntityAssetLoader(private val assetLoader: AssetLoader) : DisposableContai
         LoadingCache<Pair<EntityType, Int?>, InstancedMesh>(
             { (type, model) ->
                 try {
-                    loadMesh(type, model) ?: DEFAULT_MESH
+                    loadMesh(type, model)
+                        ?: if (type is NpcType) DEFAULT_NPC_MESH else DEFAULT_OBJECT_MESH
                 } catch (e: Exception) {
                     logger.error(e) { "Couldn't load mesh for $type (model: $model)." }
-                    DEFAULT_MESH
+                    if (type is NpcType) DEFAULT_NPC_MESH else DEFAULT_OBJECT_MESH
                 }
             },
             ::disposeObject3DResources
@@ -60,8 +60,12 @@ class EntityAssetLoader(private val assetLoader: AssetLoader) : DisposableContai
             ninjaObject,
             textures,
             maxInstances = 300,
+            defaultMaterial = MeshLambertMaterial(obj {
+                color = if (type is NpcType) DEFAULT_NPC_COLOR else DEFAULT_OBJECT_COLOR
+                side = DoubleSide
+            }),
             boundingVolumes = true,
-        )
+        ).apply { name = type.uniqueName }
     }
 
     private suspend fun loadTextures(type: EntityType, model: Int?): List<XvrTexture> {
@@ -121,23 +125,30 @@ class EntityAssetLoader(private val assetLoader: AssetLoader) : DisposableContai
     }
 
     companion object {
-        private val DEFAULT_MESH = InstancedMesh(
-            CylinderBufferGeometry(
-                radiusTop = 2.5,
-                radiusBottom = 2.5,
-                height = 18.0,
-                radialSegments = 16,
+        private val DEFAULT_NPC_COLOR = Color(0xFF0000)
+        private val DEFAULT_OBJECT_COLOR = Color(0xFFFF00)
+
+        private val DEFAULT_NPC_MESH = createCylinder(DEFAULT_NPC_COLOR)
+        private val DEFAULT_OBJECT_MESH = createCylinder(DEFAULT_OBJECT_COLOR)
+
+        private fun createCylinder(color: Color) =
+            InstancedMesh(
+                CylinderBufferGeometry(
+                    radiusTop = 2.5,
+                    radiusBottom = 2.5,
+                    height = 18.0,
+                    radialSegments = 20,
+                ).apply {
+                    translate(0.0, 9.0, 0.0)
+                    computeBoundingBox()
+                    computeBoundingSphere()
+                },
+                MeshLambertMaterial(obj { this.color = color }),
+                count = 1000,
             ).apply {
-                translate(0.0, 9.0, 0.0)
-                computeBoundingBox()
-                computeBoundingSphere()
-            },
-            MeshLambertMaterial(),
-            count = 1000,
-        ).apply {
-            // Start with 0 instances.
-            count = 0
-        }
+                // Start with 0 instances.
+                count = 0
+            }
     }
 }
 
diff --git a/web/src/main/kotlin/world/phantasmal/web/questEditor/loading/LoadingCache.kt b/web/src/main/kotlin/world/phantasmal/web/questEditor/loading/LoadingCache.kt
index b57f34c8..70f13b9a 100644
--- a/web/src/main/kotlin/world/phantasmal/web/questEditor/loading/LoadingCache.kt
+++ b/web/src/main/kotlin/world/phantasmal/web/questEditor/loading/LoadingCache.kt
@@ -8,7 +8,7 @@ class LoadingCache<K, V>(
     private val loadValue: suspend (K) -> V,
     private val disposeValue: (V) -> Unit,
 ) : TrackedDisposable() {
-    private val scope: CoroutineScope = CoroutineScope(Dispatchers.Default)
+    private val scope: CoroutineScope = CoroutineScope(SupervisorJob() + Dispatchers.Default)
     private val map = mutableMapOf<K, Deferred<V>>()
 
     val values: Collection<Deferred<V>> = map.values
diff --git a/web/src/main/kotlin/world/phantasmal/web/questEditor/rendering/AreaMeshManager.kt b/web/src/main/kotlin/world/phantasmal/web/questEditor/rendering/AreaMeshManager.kt
index 0c1525d5..64bebb17 100644
--- a/web/src/main/kotlin/world/phantasmal/web/questEditor/rendering/AreaMeshManager.kt
+++ b/web/src/main/kotlin/world/phantasmal/web/questEditor/rendering/AreaMeshManager.kt
@@ -1,5 +1,6 @@
 package world.phantasmal.web.questEditor.rendering
 
+import kotlinx.coroutines.CancellationException
 import mu.KotlinLogging
 import world.phantasmal.lib.fileFormats.quest.Episode
 import world.phantasmal.web.questEditor.loading.AreaAssetLoader
@@ -21,6 +22,8 @@ class AreaMeshManager(
         try {
             renderContext.collisionGeometry =
                 areaAssetLoader.loadCollisionGeometry(episode, areaVariant)
+        } catch (e: CancellationException) {
+            // Do nothing.
         } catch (e: Exception) {
             logger.error(e) {
                 "Couldn't load models for area ${areaVariant.area.id}, variant ${areaVariant.id}."
diff --git a/web/src/main/kotlin/world/phantasmal/web/questEditor/rendering/EntityInstancedMesh.kt b/web/src/main/kotlin/world/phantasmal/web/questEditor/rendering/EntityInstancedMesh.kt
index 20894513..22a1a0ff 100644
--- a/web/src/main/kotlin/world/phantasmal/web/questEditor/rendering/EntityInstancedMesh.kt
+++ b/web/src/main/kotlin/world/phantasmal/web/questEditor/rendering/EntityInstancedMesh.kt
@@ -59,13 +59,14 @@ class EntityInstancedMesh(
 
     private fun removeAt(index: Int) {
         val instance = instances.removeAt(index)
-        instance.mesh.count--
+        mesh.count--
 
-        for (i in index until instance.mesh.count) {
-            instance.mesh.instanceMatrix.copyAt(i, instance.mesh.instanceMatrix, i + 1)
+        for (i in index..instances.lastIndex) {
+            mesh.instanceMatrix.copyAt(i, mesh.instanceMatrix, i + 1)
             instances[i].instanceIndex = i
         }
 
+        mesh.instanceMatrix.needsUpdate = true
         instance.dispose()
     }
 
diff --git a/web/src/main/kotlin/world/phantasmal/web/questEditor/rendering/EntityMeshManager.kt b/web/src/main/kotlin/world/phantasmal/web/questEditor/rendering/EntityMeshManager.kt
index 45d6a8b2..58af7276 100644
--- a/web/src/main/kotlin/world/phantasmal/web/questEditor/rendering/EntityMeshManager.kt
+++ b/web/src/main/kotlin/world/phantasmal/web/questEditor/rendering/EntityMeshManager.kt
@@ -2,6 +2,7 @@ package world.phantasmal.web.questEditor.rendering
 
 import kotlinx.coroutines.*
 import mu.KotlinLogging
+import world.phantasmal.core.disposable.DisposableSupervisedScope
 import world.phantasmal.lib.fileFormats.quest.EntityType
 import world.phantasmal.web.externals.three.BoxHelper
 import world.phantasmal.web.externals.three.Color
@@ -19,7 +20,7 @@ class EntityMeshManager(
     private val renderContext: QuestRenderContext,
     private val entityAssetLoader: EntityAssetLoader,
 ) : DisposableContainer() {
-    private val scope: CoroutineScope = CoroutineScope(Dispatchers.Main)
+    private val scope = addDisposable(DisposableSupervisedScope(this::class, Dispatchers.Main))
 
     /**
      * Contains one [EntityInstancedMesh] per [EntityType] and model.
@@ -50,7 +51,7 @@ class EntityMeshManager(
     /**
      * Bounding box around the highlighted entity.
      */
-    private val highlightedBox = BoxHelper(color = Color(0.7, 0.7, 0.7)).apply {
+    private val highlightedBox = BoxHelper(color = Color(.7, .7, .7)).apply {
         visible = false
         renderContext.scene.add(this)
     }
@@ -58,7 +59,7 @@ class EntityMeshManager(
     /**
      * Bounding box around the selected entity.
      */
-    private val selectedBox = BoxHelper(color = Color(0.9, 0.9, 0.9)).apply {
+    private val selectedBox = BoxHelper(color = Color(.9, .9, .9)).apply {
         visible = false
         renderContext.scene.add(this)
     }
@@ -113,7 +114,7 @@ class EntityMeshManager(
     }
 
     fun remove(entity: QuestEntityModel<*, *>) {
-        loadingEntities.remove(entity)?.cancel()
+        loadingEntities.remove(entity)?.cancel("Removed.")
 
         entityMeshCache.getIfPresentNow(
             TypeAndModel(
@@ -125,7 +126,7 @@ class EntityMeshManager(
 
     @OptIn(ExperimentalCoroutinesApi::class)
     fun removeAll() {
-        loadingEntities.values.forEach { it.cancel() }
+        loadingEntities.values.forEach { it.cancel("Removed.") }
         loadingEntities.clear()
 
         for (meshContainerDeferred in entityMeshCache.values) {
@@ -144,7 +145,7 @@ class EntityMeshManager(
             attachBoxHelper(
                 highlightedBox,
                 highlightedEntityInstance,
-                instance
+                instance,
             )
             highlightedEntityInstance = instance
         }
diff --git a/web/src/main/kotlin/world/phantasmal/web/questEditor/rendering/QuestMeshManager.kt b/web/src/main/kotlin/world/phantasmal/web/questEditor/rendering/QuestMeshManager.kt
index be5dc1a0..9f39f0d4 100644
--- a/web/src/main/kotlin/world/phantasmal/web/questEditor/rendering/QuestMeshManager.kt
+++ b/web/src/main/kotlin/world/phantasmal/web/questEditor/rendering/QuestMeshManager.kt
@@ -1,9 +1,9 @@
 package world.phantasmal.web.questEditor.rendering
 
-import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.Job
 import kotlinx.coroutines.launch
+import world.phantasmal.core.disposable.DisposableSupervisedScope
 import world.phantasmal.core.disposable.Disposer
 import world.phantasmal.lib.fileFormats.quest.Episode
 import world.phantasmal.observable.value.list.ListVal
@@ -25,7 +25,7 @@ abstract class QuestMeshManager protected constructor(
     questEditorStore: QuestEditorStore,
     renderContext: QuestRenderContext,
 ) : DisposableContainer() {
-    private val scope: CoroutineScope = CoroutineScope(Dispatchers.Default)
+    private val scope = addDisposable(DisposableSupervisedScope(this::class, Dispatchers.Default))
     private val areaDisposer = addDisposable(Disposer())
     private val areaMeshManager = AreaMeshManager(renderContext, areaAssetLoader)
     private val entityMeshManager = addDisposable(
diff --git a/web/src/main/kotlin/world/phantasmal/web/questEditor/rendering/input/Evt.kt b/web/src/main/kotlin/world/phantasmal/web/questEditor/rendering/input/Evt.kt
index dde9ab35..cf94edc8 100644
--- a/web/src/main/kotlin/world/phantasmal/web/questEditor/rendering/input/Evt.kt
+++ b/web/src/main/kotlin/world/phantasmal/web/questEditor/rendering/input/Evt.kt
@@ -6,6 +6,8 @@ import world.phantasmal.web.questEditor.widgets.EntityDragEvent
 
 sealed class Evt
 
+class KeyboardEvt(val key: String) : Evt()
+
 sealed class PointerEvt : Evt() {
     abstract val buttons: Int
     abstract val shiftKeyDown: Boolean
@@ -38,6 +40,13 @@ class PointerMoveEvt(
     override val movedSinceLastPointerDown: Boolean,
 ) : PointerEvt()
 
+class PointerOutEvt(
+    override val buttons: Int,
+    override val shiftKeyDown: Boolean,
+    override val pointerDevicePosition: Vector2,
+    override val movedSinceLastPointerDown: Boolean,
+) : PointerEvt()
+
 sealed class EntityDragEvt(
     private val event: EntityDragEvent,
     /**
diff --git a/web/src/main/kotlin/world/phantasmal/web/questEditor/rendering/input/QuestInputManager.kt b/web/src/main/kotlin/world/phantasmal/web/questEditor/rendering/input/QuestInputManager.kt
index a454bd40..86e39fa7 100644
--- a/web/src/main/kotlin/world/phantasmal/web/questEditor/rendering/input/QuestInputManager.kt
+++ b/web/src/main/kotlin/world/phantasmal/web/questEditor/rendering/input/QuestInputManager.kt
@@ -1,6 +1,8 @@
 package world.phantasmal.web.questEditor.rendering.input
 
 import kotlinx.browser.window
+import org.w3c.dom.events.FocusEvent
+import org.w3c.dom.events.KeyboardEvent
 import org.w3c.dom.pointerevents.PointerEvent
 import world.phantasmal.core.disposable.Disposable
 import world.phantasmal.web.core.rendering.InputManager
@@ -17,7 +19,7 @@ import world.phantasmal.webui.DisposableContainer
 import world.phantasmal.webui.dom.disposableListener
 
 class QuestInputManager(
-    questEditorStore: QuestEditorStore,
+    private val questEditorStore: QuestEditorStore,
     private val renderContext: QuestRenderContext,
 ) : DisposableContainer(), InputManager {
     private val stateContext: StateContext
@@ -42,14 +44,18 @@ class QuestInputManager(
         }
 
     init {
-        addDisposables(
-            renderContext.canvas.disposableListener("pointerdown", ::onPointerDown)
-        )
-
         onPointerMoveListener =
             renderContext.canvas.disposableListener("pointermove", ::onPointerMove)
 
         addDisposables(
+            renderContext.canvas.disposableListener<FocusEvent>(
+                "focus",
+                { onFocus() },
+                useCapture = true,
+            ),
+            renderContext.canvas.disposableListener("pointerdown", ::onPointerDown),
+            renderContext.canvas.disposableListener("pointerout", ::onPointerOut),
+            renderContext.canvas.disposableListener("keydown", ::onKeyDown),
             renderContext.canvas.observeEntityDragEnter(::onEntityDragEnter),
             renderContext.canvas.observeEntityDragOver(::onEntityDragOver),
             renderContext.canvas.observeEntityDragLeave(::onEntityDragLeave),
@@ -91,6 +97,10 @@ class QuestInputManager(
         cameraInputManager.beforeRender()
     }
 
+    private fun onFocus() {
+        questEditorStore.makeMainUndoCurrent()
+    }
+
     private fun onPointerDown(e: PointerEvent) {
         processPointerEvent(e)
 
@@ -146,6 +156,23 @@ class QuestInputManager(
         )
     }
 
+    private fun onPointerOut(e: PointerEvent) {
+        processPointerEvent(type = null, e.clientX, e.clientY)
+
+        state = state.processEvent(
+            PointerOutEvt(
+                e.buttons.toInt(),
+                shiftKeyDown = e.shiftKey,
+                pointerDevicePosition,
+                movedSinceLastPointerDown,
+            )
+        )
+    }
+
+    private fun onKeyDown(e: KeyboardEvent) {
+        state = state.processEvent(KeyboardEvt(e.key))
+    }
+
     private fun onEntityDragEnter(e: EntityDragEvent) {
         processPointerEvent(type = null, e.clientX, e.clientY)
 
diff --git a/web/src/main/kotlin/world/phantasmal/web/questEditor/rendering/input/state/CreationState.kt b/web/src/main/kotlin/world/phantasmal/web/questEditor/rendering/input/state/CreationState.kt
index af4bd900..54cef394 100644
--- a/web/src/main/kotlin/world/phantasmal/web/questEditor/rendering/input/state/CreationState.kt
+++ b/web/src/main/kotlin/world/phantasmal/web/questEditor/rendering/input/state/CreationState.kt
@@ -36,6 +36,7 @@ class CreationState(
             else -> error("Unsupported entity type ${event.entityType::class}.")
         }
 
+    private val dragAdjust = Vector3(.0, .0, .0)
     private val pointerDevicePosition = Vector2()
     private var shouldTranslate = false
     private var shouldTranslateVertically = false
@@ -83,14 +84,14 @@ class CreationState(
             if (shouldTranslateVertically) {
                 ctx.translateEntityVertically(
                     entity,
-                    ZERO_VECTOR,
+                    dragAdjust,
                     ZERO_VECTOR,
                     pointerDevicePosition,
                 )
             } else {
                 ctx.translateEntityHorizontally(
                     entity,
-                    ZERO_VECTOR,
+                    dragAdjust,
                     ZERO_VECTOR,
                     pointerDevicePosition,
                 )
diff --git a/web/src/main/kotlin/world/phantasmal/web/questEditor/rendering/input/state/IdleState.kt b/web/src/main/kotlin/world/phantasmal/web/questEditor/rendering/input/state/IdleState.kt
index 4214f8aa..92e8d105 100644
--- a/web/src/main/kotlin/world/phantasmal/web/questEditor/rendering/input/state/IdleState.kt
+++ b/web/src/main/kotlin/world/phantasmal/web/questEditor/rendering/input/state/IdleState.kt
@@ -19,6 +19,17 @@ class IdleState(
 
     override fun processEvent(event: Evt): State {
         when (event) {
+            is KeyboardEvt -> {
+                if (entityManipulationEnabled) {
+                    val quest = ctx.quest.value
+                    val entity = ctx.selectedEntity.value
+
+                    if (quest != null && entity != null && event.key == "Delete") {
+                        ctx.deleteEntity(quest, entity)
+                    }
+                }
+            }
+
             is PointerDownEvt -> {
                 val pick = pickEntity(event.pointerDevicePosition)
 
@@ -85,6 +96,11 @@ class IdleState(
                 }
             }
 
+            is PointerOutEvt -> {
+                ctx.setHighlightedEntity(null)
+                shouldCheckHighlight = false
+            }
+
             is EntityDragEnterEvt -> {
                 val quest = ctx.quest.value
                 val area = ctx.area.value
diff --git a/web/src/main/kotlin/world/phantasmal/web/questEditor/rendering/input/state/StateContext.kt b/web/src/main/kotlin/world/phantasmal/web/questEditor/rendering/input/state/StateContext.kt
index c0b9a0b3..6dbaa989 100644
--- a/web/src/main/kotlin/world/phantasmal/web/questEditor/rendering/input/state/StateContext.kt
+++ b/web/src/main/kotlin/world/phantasmal/web/questEditor/rendering/input/state/StateContext.kt
@@ -6,6 +6,7 @@ import world.phantasmal.web.core.plusAssign
 import world.phantasmal.web.core.rendering.OrbitalCameraInputManager
 import world.phantasmal.web.externals.three.*
 import world.phantasmal.web.questEditor.actions.CreateEntityAction
+import world.phantasmal.web.questEditor.actions.DeleteEntityAction
 import world.phantasmal.web.questEditor.actions.RotateEntityAction
 import world.phantasmal.web.questEditor.actions.TranslateEntityAction
 import world.phantasmal.web.questEditor.models.*
@@ -22,6 +23,7 @@ class StateContext(
     val quest: Val<QuestModel?> = questEditorStore.currentQuest
     val area: Val<AreaModel?> = questEditorStore.currentArea
     val wave: Val<WaveModel?> = questEditorStore.selectedWave
+    val selectedEntity: Val<QuestEntityModel<*, *>?> = questEditorStore.selectedEntity
 
     fun setHighlightedEntity(entity: QuestEntityModel<*, *>?) {
         questEditorStore.setHighlightedEntity(entity)
@@ -180,6 +182,14 @@ class StateContext(
         ))
     }
 
+    fun deleteEntity(quest: QuestModel, entity: QuestEntityModel<*, *>) {
+        questEditorStore.executeAction(DeleteEntityAction(
+            ::setSelectedEntity,
+            quest,
+            entity,
+        ))
+    }
+
     /**
      * @param origin position in normalized device space.
      */
diff --git a/web/src/main/kotlin/world/phantasmal/web/questEditor/stores/AssemblyEditorStore.kt b/web/src/main/kotlin/world/phantasmal/web/questEditor/stores/AsmStore.kt
similarity index 69%
rename from web/src/main/kotlin/world/phantasmal/web/questEditor/stores/AssemblyEditorStore.kt
rename to web/src/main/kotlin/world/phantasmal/web/questEditor/stores/AsmStore.kt
index d8ab3626..2f164497 100644
--- a/web/src/main/kotlin/world/phantasmal/web/questEditor/stores/AssemblyEditorStore.kt
+++ b/web/src/main/kotlin/world/phantasmal/web/questEditor/stores/AsmStore.kt
@@ -1,35 +1,103 @@
 package world.phantasmal.web.questEditor.stores
 
 import world.phantasmal.lib.assembly.disassemble
+import world.phantasmal.observable.ChangeEvent
+import world.phantasmal.observable.Observable
+import world.phantasmal.observable.emitter
 import world.phantasmal.observable.value.Val
-import world.phantasmal.observable.value.map
+import world.phantasmal.observable.value.mutableVal
 import world.phantasmal.observable.value.trueVal
+import world.phantasmal.web.core.undo.SimpleUndo
+import world.phantasmal.web.core.undo.UndoManager
 import world.phantasmal.web.externals.monacoEditor.*
+import world.phantasmal.web.questEditor.models.QuestModel
 import world.phantasmal.webui.obj
 import world.phantasmal.webui.stores.Store
 import kotlin.js.RegExp
 
-class AssemblyEditorStore(questEditorStore: QuestEditorStore) : Store() {
-    private var _textModel: ITextModel? = null
+class AsmStore(
+    questEditorStore: QuestEditorStore,
+    private val undoManager: UndoManager,
+) : Store() {
+    private var _textModel = mutableVal<ITextModel?>(null)
+
+    private val _didUndo = emitter<Unit>()
+    private val _didRedo = emitter<Unit>()
+    private val undo = SimpleUndo(
+        undoManager,
+        "Script edits",
+        { _didUndo.emit(ChangeEvent(Unit)) },
+        { _didRedo.emit(ChangeEvent(Unit)) },
+    )
 
     val inlineStackArgs: Val<Boolean> = trueVal()
 
-    val textModel: Val<ITextModel?> =
-        map(questEditorStore.currentQuest, inlineStackArgs) { quest, inlineArgs ->
-            _textModel?.dispose()
-
-            _textModel =
-                if (quest == null) null
-                else {
-                    val assembly = disassemble(quest.bytecodeIr, inlineArgs)
-                    createModel(assembly.joinToString("\n"), ASM_LANG_ID)
-                }
-
-            _textModel
-        }
+    val textModel: Val<ITextModel?> = _textModel
 
     val editingEnabled: Val<Boolean> = questEditorStore.questEditingEnabled
 
+    val didUndo: Observable<Unit> = _didUndo
+    val didRedo: Observable<Unit> = _didRedo
+
+    init {
+        observe(questEditorStore.currentQuest, inlineStackArgs) { quest, inlineArgs ->
+            _textModel.value?.dispose()
+            _textModel.value = quest?.let { createModel(quest, inlineArgs) }
+        }
+    }
+
+    fun makeUndoCurrent() {
+        undoManager.setCurrent(undo)
+    }
+
+    private fun createModel(quest: QuestModel, inlineArgs: Boolean): ITextModel {
+        val assembly = disassemble(quest.bytecodeIr, inlineArgs)
+        val model = createModel(assembly.joinToString("\n"), ASM_LANG_ID)
+        addModelChangeListener(model)
+        return model
+    }
+
+    /**
+     * Sets up undo/redo, code analysis and breakpoint updates on model change.
+     */
+    private fun addModelChangeListener(model: ITextModel) {
+        val initialVersion = model.getAlternativeVersionId()
+        var currentVersion = initialVersion
+        var lastVersion = initialVersion
+
+        model.onDidChangeContent {
+            val version = model.getAlternativeVersionId()
+
+            if (version < currentVersion) {
+                // Undoing.
+                undo.canRedo.value = true
+
+                if (version == initialVersion) {
+                    undo.canUndo.value = false
+                }
+            } else {
+                // Redoing.
+                if (version <= lastVersion) {
+                    if (version == lastVersion) {
+                        undo.canRedo.value = false
+                    }
+                } else {
+                    undo.canRedo.value = false
+
+                    if (currentVersion > lastVersion) {
+                        lastVersion = currentVersion
+                    }
+                }
+
+                undo.canUndo.value = true
+            }
+
+            currentVersion = version
+
+            // TODO: Code analysis and breakpoint update.
+        }
+    }
+
     companion object {
         const val ASM_LANG_ID = "psoasm"
 
diff --git a/web/src/main/kotlin/world/phantasmal/web/questEditor/stores/QuestEditorStore.kt b/web/src/main/kotlin/world/phantasmal/web/questEditor/stores/QuestEditorStore.kt
index be2ede4b..84776dd8 100644
--- a/web/src/main/kotlin/world/phantasmal/web/questEditor/stores/QuestEditorStore.kt
+++ b/web/src/main/kotlin/world/phantasmal/web/questEditor/stores/QuestEditorStore.kt
@@ -18,16 +18,15 @@ import world.phantasmal.webui.stores.Store
 private val logger = KotlinLogging.logger {}
 
 class QuestEditorStore(
-    private val uiStore: UiStore,
+    uiStore: UiStore,
     private val areaStore: AreaStore,
+    private val undoManager: UndoManager,
 ) : Store() {
     private val _currentQuest = mutableVal<QuestModel?>(null)
     private val _currentArea = mutableVal<AreaModel?>(null)
     private val _selectedWave = mutableVal<WaveModel?>(null)
     private val _highlightedEntity = mutableVal<QuestEntityModel<*, *>?>(null)
     private val _selectedEntity = mutableVal<QuestEntityModel<*, *>?>(null)
-
-    private val undoManager = UndoManager()
     private val mainUndo = UndoStack(undoManager)
 
     val runner = QuestRunner()
@@ -76,21 +75,19 @@ class QuestEditorStore(
     }
 
     fun makeMainUndoCurrent() {
-        mainUndo.makeCurrent()
+        undoManager.setCurrent(mainUndo)
     }
 
     fun undo() {
-        require(canUndo.value) { "Can't undo at the moment." }
         undoManager.undo()
     }
 
     fun redo() {
-        require(canRedo.value) { "Can't redo at the moment." }
         undoManager.redo()
     }
 
     suspend fun setCurrentQuest(quest: QuestModel?) {
-        mainUndo.reset()
+        undoManager.reset()
 
         // TODO: Stop runner.
 
diff --git a/web/src/main/kotlin/world/phantasmal/web/questEditor/widgets/AssemblyEditorWidget.kt b/web/src/main/kotlin/world/phantasmal/web/questEditor/widgets/AsmEditorWidget.kt
similarity index 50%
rename from web/src/main/kotlin/world/phantasmal/web/questEditor/widgets/AssemblyEditorWidget.kt
rename to web/src/main/kotlin/world/phantasmal/web/questEditor/widgets/AsmEditorWidget.kt
index cffa7dbc..c3d5932b 100644
--- a/web/src/main/kotlin/world/phantasmal/web/questEditor/widgets/AssemblyEditorWidget.kt
+++ b/web/src/main/kotlin/world/phantasmal/web/questEditor/widgets/AsmEditorWidget.kt
@@ -2,20 +2,19 @@ package world.phantasmal.web.questEditor.widgets
 
 import org.w3c.dom.Node
 import world.phantasmal.core.disposable.disposable
-import world.phantasmal.web.externals.monacoEditor.IStandaloneCodeEditor
-import world.phantasmal.web.externals.monacoEditor.create
-import world.phantasmal.web.externals.monacoEditor.defineTheme
-import world.phantasmal.web.externals.monacoEditor.set
-import world.phantasmal.web.questEditor.controllers.AssemblyEditorController
+import world.phantasmal.web.externals.monacoEditor.*
+import world.phantasmal.web.questEditor.controllers.AsmController
 import world.phantasmal.webui.dom.div
 import world.phantasmal.webui.obj
 import world.phantasmal.webui.widgets.Widget
 
-class AssemblyEditorWidget(private val ctrl: AssemblyEditorController) : Widget() {
+class AsmEditorWidget(private val ctrl: AsmController) : Widget() {
     private lateinit var editor: IStandaloneCodeEditor
 
     override fun Node.createElement() =
         div {
+            className = "pw-quest-editor-asm-editor"
+
             editor = create(this, obj {
                 theme = "phantasmal-world"
                 scrollBeyondLastLine = false
@@ -34,13 +33,53 @@ class AssemblyEditorWidget(private val ctrl: AssemblyEditorController) : Widget(
             observe(ctrl.readOnly) { editor.updateOptions(obj { readOnly = it }) }
 
             addDisposable(size.observe { (size) ->
-                editor.layout(obj {
-                    width = size.width
-                    height = size.height
-                })
+                if (size.width > .0 && size.height > .0) {
+                    editor.layout(obj {
+                        width = size.width
+                        height = size.height
+                    })
+                }
             })
+
+            // Add VSCode keybinding for command palette.
+            val quickCommand = editor.getAction("editor.action.quickCommand")
+
+            editor.addAction(object : IActionDescriptor {
+                override var id = "editor.action.quickCommand"
+                override var label = "Command Palette"
+                override var keybindings =
+                    arrayOf(KeyMod.CtrlCmd or KeyMod.Shift or KeyCode.KEY_P)
+
+                override fun run(editor: ICodeEditor, vararg args: dynamic) {
+                    quickCommand.run()
+                }
+            })
+
+            // Undo/redo.
+            observe(ctrl.didUndo) {
+                editor.focus()
+                editor.trigger(
+                    source = AsmEditorWidget::class.simpleName,
+                    handlerId = "undo",
+                    payload = undefined
+                )
+            }
+
+            observe(ctrl.didRedo) {
+                editor.trigger(
+                    source = AsmEditorWidget::class.simpleName,
+                    handlerId = "redo",
+                    payload = undefined
+                )
+            }
+
+            editor.onDidFocusEditorWidget(ctrl::makeUndoCurrent)
         }
 
+    override fun focus() {
+        editor.focus()
+    }
+
     companion object {
         init {
             defineTheme("phantasmal-world", obj {
@@ -61,6 +100,14 @@ class AssemblyEditorWidget(private val ctrl: AssemblyEditorController) : Widget(
                     this["editor.lineHighlightBackground"] = "#202020"
                 }
             })
+
+            @Suppress("CssUnusedSymbol")
+            // language=css
+            style("""
+                .pw-quest-editor-asm-editor {
+                    flex-grow: 1;
+                }
+            """.trimIndent())
         }
     }
 }
diff --git a/web/src/main/kotlin/world/phantasmal/web/questEditor/widgets/AsmToolbarWidget.kt b/web/src/main/kotlin/world/phantasmal/web/questEditor/widgets/AsmToolbarWidget.kt
new file mode 100644
index 00000000..a01df3d5
--- /dev/null
+++ b/web/src/main/kotlin/world/phantasmal/web/questEditor/widgets/AsmToolbarWidget.kt
@@ -0,0 +1,28 @@
+package world.phantasmal.web.questEditor.widgets
+
+import org.w3c.dom.Node
+import world.phantasmal.web.questEditor.controllers.AsmController
+import world.phantasmal.webui.dom.div
+import world.phantasmal.webui.widgets.Checkbox
+import world.phantasmal.webui.widgets.Toolbar
+import world.phantasmal.webui.widgets.Widget
+
+class AsmToolbarWidget(private val ctrl: AsmController) : Widget() {
+    override fun Node.createElement() =
+        div {
+            className = "pw-quest-editor-asm-toolbar"
+
+            addChild(Toolbar(
+                enabled = ctrl.enabled,
+                children = listOf(
+                    Checkbox(
+                        enabled = ctrl.inlineStackArgsEnabled,
+                        tooltip = ctrl.inlineStackArgsTooltip,
+                        label = "Inline args",
+                        checked = ctrl.inlineStackArgs,
+                        onChange = ctrl::setInlineStackArgs,
+                    )
+                )
+            ))
+        }
+}
diff --git a/web/src/main/kotlin/world/phantasmal/web/questEditor/widgets/AsmWidget.kt b/web/src/main/kotlin/world/phantasmal/web/questEditor/widgets/AsmWidget.kt
new file mode 100644
index 00000000..f6bca558
--- /dev/null
+++ b/web/src/main/kotlin/world/phantasmal/web/questEditor/widgets/AsmWidget.kt
@@ -0,0 +1,36 @@
+package world.phantasmal.web.questEditor.widgets
+
+import org.w3c.dom.Node
+import world.phantasmal.web.questEditor.controllers.AsmController
+import world.phantasmal.webui.dom.div
+import world.phantasmal.webui.widgets.Widget
+
+class AsmWidget(private val ctrl: AsmController) : Widget() {
+    private lateinit var editorWidget: AsmEditorWidget
+
+    override fun Node.createElement() =
+        div {
+            className = "pw-quest-editor-asm"
+
+            addChild(AsmToolbarWidget(ctrl))
+            editorWidget = addChild(AsmEditorWidget(ctrl))
+        }
+
+    override fun focus() {
+        editorWidget.focus()
+    }
+
+    companion object {
+        init {
+            @Suppress("CssUnusedSymbol")
+            // language=css
+            style("""
+                .pw-quest-editor-asm {
+                    display: flex;
+                    flex-direction: column;
+                    overflow: hidden;
+                }
+            """.trimIndent())
+        }
+    }
+}
diff --git a/web/src/main/kotlin/world/phantasmal/web/questEditor/widgets/EntityInfoWidget.kt b/web/src/main/kotlin/world/phantasmal/web/questEditor/widgets/EntityInfoWidget.kt
index 97fe722d..79374af3 100644
--- a/web/src/main/kotlin/world/phantasmal/web/questEditor/widgets/EntityInfoWidget.kt
+++ b/web/src/main/kotlin/world/phantasmal/web/questEditor/widgets/EntityInfoWidget.kt
@@ -13,6 +13,8 @@ class EntityInfoWidget(private val ctrl: EntityInfoController) : Widget(enabled
             className = "pw-quest-editor-entity-info"
             tabIndex = -1
 
+            addEventListener("focus", { ctrl.focused() }, true)
+
             table {
                 hidden(ctrl.unavailable)
 
@@ -113,11 +115,6 @@ class EntityInfoWidget(private val ctrl: EntityInfoController) : Widget(enabled
             ))
         }
 
-    override fun focus() {
-        super.focus()
-        ctrl.focused()
-    }
-
     companion object {
         private const val COORD_CLASS = "pw-quest-editor-entity-info-coord"
 
diff --git a/web/src/main/kotlin/world/phantasmal/web/questEditor/widgets/EntityListWidget.kt b/web/src/main/kotlin/world/phantasmal/web/questEditor/widgets/EntityListWidget.kt
index fc903303..e3604eb4 100644
--- a/web/src/main/kotlin/world/phantasmal/web/questEditor/widgets/EntityListWidget.kt
+++ b/web/src/main/kotlin/world/phantasmal/web/questEditor/widgets/EntityListWidget.kt
@@ -17,7 +17,6 @@ class EntityListWidget(
     override fun Node.createElement() =
         div {
             className = "pw-quest-editor-entity-list"
-            tabIndex = -1
 
             div {
                 className = "pw-quest-editor-entity-list-inner"
diff --git a/web/src/main/kotlin/world/phantasmal/web/questEditor/widgets/NpcCountsWidget.kt b/web/src/main/kotlin/world/phantasmal/web/questEditor/widgets/NpcCountsWidget.kt
index e8a08c8a..0feca6ae 100644
--- a/web/src/main/kotlin/world/phantasmal/web/questEditor/widgets/NpcCountsWidget.kt
+++ b/web/src/main/kotlin/world/phantasmal/web/questEditor/widgets/NpcCountsWidget.kt
@@ -12,6 +12,9 @@ class NpcCountsWidget(
     override fun Node.createElement() =
         div {
             className = "pw-quest-editor-npc-counts"
+            tabIndex = -1
+
+            addEventListener("focus", { ctrl.focused() }, true)
 
             table {
                 hidden(ctrl.unavailable)
diff --git a/web/src/main/kotlin/world/phantasmal/web/questEditor/widgets/QuestEditorToolbarWidget.kt b/web/src/main/kotlin/world/phantasmal/web/questEditor/widgets/QuestEditorToolbarWidget.kt
index 2fa29d18..3ee0f099 100644
--- a/web/src/main/kotlin/world/phantasmal/web/questEditor/widgets/QuestEditorToolbarWidget.kt
+++ b/web/src/main/kotlin/world/phantasmal/web/questEditor/widgets/QuestEditorToolbarWidget.kt
@@ -25,7 +25,7 @@ class QuestEditorToolbarWidget(private val ctrl: QuestEditorToolbarController) :
                         text = "Open file...",
                         tooltip = value("Open a quest file (Ctrl-O)"),
                         iconLeft = Icon.File,
-                        accept = ".bin, .dat, .qst",
+                        accept = ctrl.openFileAccept,
                         multiple = true,
                         filesSelected = { files -> scope.launch { ctrl.openFiles(files) } },
                     ),
@@ -45,11 +45,11 @@ class QuestEditorToolbarWidget(private val ctrl: QuestEditorToolbarController) :
                     ),
                     Select(
                         enabled = ctrl.areaSelectEnabled,
-                        itemsVal = ctrl.areas,
+                        items = ctrl.areas,
                         itemToString = { it.label },
-                        selectedVal = ctrl.currentArea,
+                        selected = ctrl.currentArea,
                         onSelect = ctrl::setCurrentArea,
-                    )
+                    ),
                 )
             ))
         }
diff --git a/web/src/main/kotlin/world/phantasmal/web/questEditor/widgets/QuestEditorWidget.kt b/web/src/main/kotlin/world/phantasmal/web/questEditor/widgets/QuestEditorWidget.kt
index 6f1a2c1d..78751cde 100644
--- a/web/src/main/kotlin/world/phantasmal/web/questEditor/widgets/QuestEditorWidget.kt
+++ b/web/src/main/kotlin/world/phantasmal/web/questEditor/widgets/QuestEditorWidget.kt
@@ -3,7 +3,7 @@ package world.phantasmal.web.questEditor.widgets
 import org.w3c.dom.Node
 import world.phantasmal.web.core.widgets.DockWidget
 import world.phantasmal.web.questEditor.controllers.QuestEditorController
-import world.phantasmal.web.questEditor.controllers.QuestEditorController.Companion.ASSEMBLY_EDITOR_WIDGET_ID
+import world.phantasmal.web.questEditor.controllers.QuestEditorController.Companion.ASM_WIDGET_ID
 import world.phantasmal.web.questEditor.controllers.QuestEditorController.Companion.ENTITY_INFO_WIDGET_ID
 import world.phantasmal.web.questEditor.controllers.QuestEditorController.Companion.EVENTS_WIDGET_ID
 import world.phantasmal.web.questEditor.controllers.QuestEditorController.Companion.NPC_COUNTS_WIDGET_ID
@@ -24,7 +24,7 @@ class QuestEditorWidget(
     private val createNpcCountsWidget: () -> NpcCountsWidget,
     private val createEntityInfoWidget: () -> EntityInfoWidget,
     private val createQuestRendererWidget: () -> QuestRendererWidget,
-    private val createAssemblyEditorWidget: () -> AssemblyEditorWidget,
+    private val createAsmWidget: () -> AsmWidget,
     private val createNpcListWidget: () -> EntityListWidget,
     private val createObjectListWidget: () -> EntityListWidget,
 ) : Widget() {
@@ -41,7 +41,7 @@ class QuestEditorWidget(
                         NPC_COUNTS_WIDGET_ID -> createNpcCountsWidget()
                         ENTITY_INFO_WIDGET_ID -> createEntityInfoWidget()
                         QUEST_RENDERER_WIDGET_ID -> createQuestRendererWidget()
-                        ASSEMBLY_EDITOR_WIDGET_ID -> createAssemblyEditorWidget()
+                        ASM_WIDGET_ID -> createAsmWidget()
                         NPC_LIST_WIDGET_ID -> createNpcListWidget()
                         OBJECT_LIST_WIDGET_ID -> createObjectListWidget()
                         EVENTS_WIDGET_ID -> null // TODO: EventsWidget.
diff --git a/web/src/main/kotlin/world/phantasmal/web/questEditor/widgets/QuestInfoWidget.kt b/web/src/main/kotlin/world/phantasmal/web/questEditor/widgets/QuestInfoWidget.kt
index d8a99572..b186b45f 100644
--- a/web/src/main/kotlin/world/phantasmal/web/questEditor/widgets/QuestInfoWidget.kt
+++ b/web/src/main/kotlin/world/phantasmal/web/questEditor/widgets/QuestInfoWidget.kt
@@ -15,6 +15,8 @@ class QuestInfoWidget(private val ctrl: QuestInfoController) : Widget(enabled =
             className = "pw-quest-editor-quest-info"
             tabIndex = -1
 
+            addEventListener("focus", { ctrl.focused() }, true)
+
             table {
                 hidden(ctrl.unavailable)
 
@@ -92,11 +94,6 @@ class QuestInfoWidget(private val ctrl: QuestInfoController) : Widget(enabled =
             ))
         }
 
-    override fun focus() {
-        super.focus()
-        ctrl.focused()
-    }
-
     companion object {
         init {
             @Suppress("CssUnusedSymbol")
diff --git a/webui/build.gradle.kts b/webui/build.gradle.kts
index 7d631a7b..fef648f0 100644
--- a/webui/build.gradle.kts
+++ b/webui/build.gradle.kts
@@ -8,12 +8,9 @@ kotlin {
     }
 }
 
-val coroutinesVersion: String by project.ext
-
 dependencies {
     api(project(":core"))
     api(project(":observable"))
-    api("org.jetbrains.kotlinx:kotlinx-coroutines-core:$coroutinesVersion")
     implementation(npm("@fortawesome/fontawesome-free", "^5.13.1"))
 
     testImplementation(kotlin("test-js"))
diff --git a/webui/src/main/kotlin/world/phantasmal/webui/Files.kt b/webui/src/main/kotlin/world/phantasmal/webui/Files.kt
index d2c34197..1c63aa39 100644
--- a/webui/src/main/kotlin/world/phantasmal/webui/Files.kt
+++ b/webui/src/main/kotlin/world/phantasmal/webui/Files.kt
@@ -9,19 +9,21 @@ import org.w3c.dom.asList
 import org.w3c.files.File
 import org.w3c.files.FileReader
 
-fun openFiles(accept: String = "", multiple: Boolean = false, callback: (List<File>) -> Unit) {
-    val el = document.createElement("input") as HTMLInputElement
-    el.type = "file"
-    el.accept = accept
-    el.multiple = multiple
+@OptIn(ExperimentalCoroutinesApi::class)
+suspend fun selectFiles(accept: String = "", multiple: Boolean = false): List<File> =
+    suspendCancellableCoroutine { cont ->
+        val el = document.createElement("input") as HTMLInputElement
+        el.type = "file"
+        el.accept = accept
+        el.multiple = multiple
 
-    el.onchange = {
-        callback(el.files?.asList() ?: emptyList())
+        el.onchange = {
+            cont.resume(el.files?.asList() ?: emptyList()) {}
+        }
+
+        el.click()
     }
 
-    el.click()
-}
-
 @OptIn(ExperimentalCoroutinesApi::class)
 suspend fun readFile(file: File): ArrayBuffer = suspendCancellableCoroutine { cont ->
     val reader = FileReader()
diff --git a/webui/src/main/kotlin/world/phantasmal/webui/dom/Dom.kt b/webui/src/main/kotlin/world/phantasmal/webui/dom/Dom.kt
index 8c8fe212..1f67833c 100644
--- a/webui/src/main/kotlin/world/phantasmal/webui/dom/Dom.kt
+++ b/webui/src/main/kotlin/world/phantasmal/webui/dom/Dom.kt
@@ -23,6 +23,19 @@ fun <E : Event> EventTarget.disposableListener(
     }
 }
 
+fun <E : Event> EventTarget.disposableListener(
+    type: String,
+    listener: (E) -> Unit,
+    useCapture: Boolean,
+): Disposable {
+    @Suppress("UNCHECKED_CAST")
+    addEventListener(type, listener as (Event) -> Unit, useCapture)
+
+    return disposable {
+        removeEventListener(type, listener)
+    }
+}
+
 fun Element.disposablePointerDrag(
     onPointerDown: (e: PointerEvent) -> Boolean,
     onPointerMove: (movedX: Int, movedY: Int, e: PointerEvent) -> Boolean,
diff --git a/webui/src/main/kotlin/world/phantasmal/webui/stores/Store.kt b/webui/src/main/kotlin/world/phantasmal/webui/stores/Store.kt
index 9bf9e7c0..d6f75476 100644
--- a/webui/src/main/kotlin/world/phantasmal/webui/stores/Store.kt
+++ b/webui/src/main/kotlin/world/phantasmal/webui/stores/Store.kt
@@ -1,15 +1,9 @@
 package world.phantasmal.webui.stores
 
-import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Dispatchers
-import kotlinx.coroutines.cancel
+import world.phantasmal.core.disposable.DisposableSupervisedScope
 import world.phantasmal.webui.DisposableContainer
 
 abstract class Store : DisposableContainer() {
-    protected val scope: CoroutineScope = CoroutineScope(Dispatchers.Default)
-
-    override fun internalDispose() {
-        scope.cancel("Store disposed.")
-        super.internalDispose()
-    }
+    protected val scope = addDisposable(DisposableSupervisedScope(this::class, Dispatchers.Default))
 }
diff --git a/webui/src/main/kotlin/world/phantasmal/webui/widgets/Checkbox.kt b/webui/src/main/kotlin/world/phantasmal/webui/widgets/Checkbox.kt
new file mode 100644
index 00000000..d9f00b4e
--- /dev/null
+++ b/webui/src/main/kotlin/world/phantasmal/webui/widgets/Checkbox.kt
@@ -0,0 +1,34 @@
+package world.phantasmal.webui.widgets
+
+import org.w3c.dom.Node
+import world.phantasmal.observable.value.Val
+import world.phantasmal.observable.value.nullVal
+import world.phantasmal.observable.value.trueVal
+import world.phantasmal.webui.dom.input
+
+class Checkbox(
+    visible: Val<Boolean> = trueVal(),
+    enabled: Val<Boolean> = trueVal(),
+    tooltip: Val<String?> = nullVal(),
+    label: String? = null,
+    labelVal: Val<String>? = null,
+    preferredLabelPosition: LabelPosition = LabelPosition.After,
+    private val checked: Val<Boolean>? = null,
+    private val onChange: ((Boolean) -> Unit)? = null,
+) : LabelledControl(visible, enabled, tooltip, label, labelVal, preferredLabelPosition) {
+    override fun Node.createElement() =
+        input {
+            className = "pw-checkbox"
+            type = "checkbox"
+
+            if (this@Checkbox.checked != null) {
+                observe(this@Checkbox.checked) {
+                    checked = it
+                }
+            }
+
+            if (onChange != null) {
+                onchange = { onChange.invoke(checked) }
+            }
+        }
+}
diff --git a/webui/src/main/kotlin/world/phantasmal/webui/widgets/FileButton.kt b/webui/src/main/kotlin/world/phantasmal/webui/widgets/FileButton.kt
index 725f2905..3417c774 100644
--- a/webui/src/main/kotlin/world/phantasmal/webui/widgets/FileButton.kt
+++ b/webui/src/main/kotlin/world/phantasmal/webui/widgets/FileButton.kt
@@ -1,12 +1,13 @@
 package world.phantasmal.webui.widgets
 
+import kotlinx.coroutines.launch
 import org.w3c.dom.HTMLElement
 import org.w3c.files.File
 import world.phantasmal.observable.value.Val
 import world.phantasmal.observable.value.nullVal
 import world.phantasmal.observable.value.trueVal
 import world.phantasmal.webui.dom.Icon
-import world.phantasmal.webui.openFiles
+import world.phantasmal.webui.selectFiles
 
 class FileButton(
     visible: Val<Boolean> = trueVal(),
@@ -25,7 +26,9 @@ class FileButton(
 
         if (filesSelected != null) {
             element.onclick = {
-                openFiles(accept, multiple, filesSelected)
+                scope.launch {
+                    filesSelected.invoke(selectFiles(accept, multiple))
+                }
             }
         }
     }
diff --git a/webui/src/main/kotlin/world/phantasmal/webui/widgets/Select.kt b/webui/src/main/kotlin/world/phantasmal/webui/widgets/Select.kt
index 96ab4a59..104df9b5 100644
--- a/webui/src/main/kotlin/world/phantasmal/webui/widgets/Select.kt
+++ b/webui/src/main/kotlin/world/phantasmal/webui/widgets/Select.kt
@@ -4,6 +4,7 @@ import org.w3c.dom.Node
 import org.w3c.dom.events.KeyboardEvent
 import org.w3c.dom.events.MouseEvent
 import world.phantasmal.observable.value.*
+import world.phantasmal.observable.value.list.emptyListVal
 import world.phantasmal.webui.dom.Icon
 import world.phantasmal.webui.dom.div
 
@@ -14,11 +15,9 @@ class Select<T : Any>(
     label: String? = null,
     labelVal: Val<String>? = null,
     preferredLabelPosition: LabelPosition = LabelPosition.Before,
-    items: List<T>? = null,
-    itemsVal: Val<List<T>>? = null,
+    items: Val<List<T>>? = null,
     private val itemToString: (T) -> String = Any::toString,
-    selected: T? = null,
-    selectedVal: Val<T?>? = null,
+    selected: Val<T?>? = null,
     private val onSelect: (T) -> Unit = {},
 ) : LabelledControl(
     visible,
@@ -28,8 +27,8 @@ class Select<T : Any>(
     labelVal,
     preferredLabelPosition,
 ) {
-    private val items: Val<List<T>> = itemsVal ?: value(items ?: emptyList())
-    private val selected: Val<T?> = selectedVal ?: value(selected)
+    private val items: Val<List<T>> = items ?: emptyListVal()
+    private val selected: Val<T?> = selected ?: nullVal()
 
     private val buttonText = mutableVal(" ")
     private val menuVisible = mutableVal(false)
diff --git a/webui/src/main/kotlin/world/phantasmal/webui/widgets/Toolbar.kt b/webui/src/main/kotlin/world/phantasmal/webui/widgets/Toolbar.kt
index 75965245..187ec9c3 100644
--- a/webui/src/main/kotlin/world/phantasmal/webui/widgets/Toolbar.kt
+++ b/webui/src/main/kotlin/world/phantasmal/webui/widgets/Toolbar.kt
@@ -5,6 +5,9 @@ import world.phantasmal.observable.value.Val
 import world.phantasmal.observable.value.trueVal
 import world.phantasmal.webui.dom.div
 
+/**
+ * Takes ownership of the given [children].
+ */
 class Toolbar(
     visible: Val<Boolean> = trueVal(),
     enabled: Val<Boolean> = trueVal(),
diff --git a/webui/src/main/kotlin/world/phantasmal/webui/widgets/Widget.kt b/webui/src/main/kotlin/world/phantasmal/webui/widgets/Widget.kt
index 920e69fc..4f1aa8dd 100644
--- a/webui/src/main/kotlin/world/phantasmal/webui/widgets/Widget.kt
+++ b/webui/src/main/kotlin/world/phantasmal/webui/widgets/Widget.kt
@@ -1,11 +1,11 @@
 package world.phantasmal.webui.widgets
 
 import kotlinx.browser.document
-import kotlinx.coroutines.CoroutineScope
-import kotlinx.coroutines.MainScope
+import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.cancel
 import org.w3c.dom.*
 import org.w3c.dom.pointerevents.PointerEvent
+import world.phantasmal.core.disposable.DisposableSupervisedScope
 import world.phantasmal.core.disposable.Disposer
 import world.phantasmal.observable.Observable
 import world.phantasmal.observable.value.*
@@ -65,7 +65,7 @@ abstract class Widget(
         el
     }
 
-    protected val scope: CoroutineScope = MainScope()
+    protected val scope = addDisposable(DisposableSupervisedScope(this::class, Dispatchers.Main))
 
     /**
      * This widget's outermost DOM element.