support scanning for message receivers from inside a block editor

HISTORY.md

@@ -12,7 +12,8 @@
     * German
 
 ### 2020-09-04
-* byob, blocks, objects: refactored scanning for message senders 
+* byob, blocks, objects: refactored scanning for message senders
+* blocks: support scanning for message receivers from inside a block editor 
 
 ### 2020-09-03
 * byob: experimental: Inspect & export dependencies for global custom blocks (shift-right-click for context menu)

src/blocks.js

@@ -3130,7 +3130,9 @@ BlockMorph.prototype.userMenu = function () {
 };
 
 BlockMorph.prototype.showMessageUsers = function () {
-    var ide = this.parentThatIsA(IDE_Morph),
+    var ide = this.parentThatIsA(IDE_Morph) ||
+            this.parentThatIsA(BlockEditorMorph)
+                .target.parentThatIsA(IDE_Morph),
         corral = ide.corral,
         getter = (this.selector.indexOf('receive') === 0) ?
             'allSendersOf' : 'allHatBlocksFor',