enabled change-of-scene events for user-induced scene switches, made them user-stoppable

HISTORY.md

@@ -34,7 +34,8 @@
     * Chinese, thanks, Simon!
 
 ### 2021-09-07
-* blocks, objects, threads: new change-of-scene event 
+* blocks, objects, threads: new change-of-scene event
+* gui, threads: enabled change-of-scene events for user-induced scene switches, made them user-stoppable
 
 ### 2021-09-06
 * blocks: fixed exporting comment pics from inside the block editor, thanks, Jadga, for the report!

snap.html

@@ -20,7 +20,7 @@
         <script src="src/threads.js?version=2021-09-07"></script>
         <script src="src/objects.js?version=2021-09-07"></script>
         <script src="src/scenes.js?version=2021-07-21"></script>
-        <script src="src/gui.js?version=2021-09-06"></script>
+        <script src="src/gui.js?version=2021-09-07"></script>
         <script src="src/paint.js?version=2021-07-05"></script>
         <script src="src/lists.js?version=2021-07-19"></script>
         <script src="src/byob.js?version=2021-08-03"></script>

src/gui.js

@@ -85,7 +85,7 @@ Animation, BoxMorph, BlockDialogMorph, RingMorph, Project, ZERO, BLACK*/
 
 // Global stuff ////////////////////////////////////////////////////////
 
-modules.gui = '2021-Auggust-06';
+modules.gui = '2021-September-07';
 
 // Declarations
 
@@ -5781,6 +5781,7 @@ IDE_Morph.prototype.switchToScene = function (scene, refreshAlbum) {
     }
     this.toggleAppMode(appMode);
     this.world().keyboardFocus = this.stage;
+    this.stage.fireChangeOfSceneEvent();
 };
 
 IDE_Morph.prototype.setURL = function (str) {

src/threads.js

@@ -4710,6 +4710,7 @@ Process.prototype.doSwitchToScene = function (id) {
         ide, scenes, num, scene;
 
     this.assertAlive(rcvr);
+    if (this.readyToTerminate) {return; } // let the user press "stop" or "esc"
     ide = rcvr.parentThatIsA(IDE_Morph);
     scenes = ide.scenes;
 
@@ -4735,7 +4736,6 @@ Process.prototype.doSwitchToScene = function (id) {
             break;
         }
         ide.switchToScene(scenes.at(idx));
-        ide.stage.fireChangeOfSceneEvent();
         return;
     }
 
@@ -4749,7 +4749,6 @@ Process.prototype.doSwitchToScene = function (id) {
     }
 
     ide.switchToScene(scene);
-    ide.stage.fireChangeOfSceneEvent();
 };