From 941664eef407050510a47e7377acd8c0379dabb1 Mon Sep 17 00:00:00 2001
From: jmoenig <jens@moenig.org>
Date: Wed, 8 Sep 2021 18:05:29 +0200
Subject: [PATCH] disabled "when this scene starts" hat blocks to directly
 switch to another scene

---
 HISTORY.md     | 1 +
 src/threads.js | 7 ++++++-
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/HISTORY.md b/HISTORY.md
index 48b43e60..a8e1bd3c 100755
--- a/HISTORY.md
+++ b/HISTORY.md
@@ -37,6 +37,7 @@
 * objects: changed category for "switch to scene" to control
 * blocks, objects, threads: new hat block for "when this scene starts"
 * blocks, threads: changed "switch to scene" to be a stop block
+* threads: disabled "when this scene starts" hat blocks to directly switch to another scene
 
 ### 2021-09-07
 * blocks, objects, threads: new change-of-scene event
diff --git a/src/threads.js b/src/threads.js
index 7e44c76d..3eef925f 100644
--- a/src/threads.js
+++ b/src/threads.js
@@ -4710,7 +4710,12 @@ Process.prototype.doSwitchToScene = function (id) {
         ide, scenes, num, scene;
 
     this.assertAlive(rcvr);
-    if (this.readyToTerminate) {return; } // let the user press "stop" or "esc"
+    if (this.readyToTerminate || this.topBlock.selector === 'receiveOnScene') {
+        // let the user press "stop" or "esc",
+        // prevent "when this scene starts" hat blocks from directly
+        // switching to another
+        return;
+    }
     ide = rcvr.parentThatIsA(IDE_Morph);
     scenes = ide.scenes;