fixed #670 and #1804

HISTORY.md

@@ -89,6 +89,7 @@
 ### 2019-06-03
 * Threads: fixed #2249, predicates inside generic WHEN hats should be able to pass upvars
 * Blocks: fixed #1740
+* Blocks: fixed #670 and #1804
 
 ### 2019-06-02
 * Objects, Store: made "pen down?" and "shown?" attributes watchable onstage

snap.html

@@ -6,7 +6,7 @@
         <link rel="shortcut icon" href="src/favicon.ico">
         <script type="text/javascript" src="src/morphic.js?version=2019-05-21"></script>
         <script type="text/javascript" src="src/widgets.js?version=2019-04-05"></script>
-        <script type="text/javascript" src="src/blocks.js?version=2019-06-03"></script>
+        <script type="text/javascript" src="src/blocks.js?version=2019-06-03_1"></script>
         <script type="text/javascript" src="src/threads.js?version=2019-06-03"></script>
         <script type="text/javascript" src="src/objects.js?version=2019-06-02"></script>
         <script type="text/javascript" src="src/gui.js?version=2019-05-29"></script>

src/blocks.js

@@ -12447,7 +12447,23 @@ CommentMorph.prototype.userMenu = function () {
     menu.addItem(
         "duplicate",
         function () {
-            myself.fullCopy().pickUp(myself.world());
+            var dup = myself.fullCopy(),
+                ide = myself.parentThatIsA(IDE_Morph),
+                blockEditor = myself.parentThatIsA(BlockEditorMorph),
+                world = myself.world();
+            dup.pickUp(world);
+            // register the drop-origin, so the comment can
+            // slide back to its former situation if dropped
+            // somewhere where it gets rejected
+            if (!ide && blockEditor) {
+                ide = blockEditor.target.parentThatIsA(IDE_Morph);
+            }
+            if (ide) {
+                world.hand.grabOrigin = {
+                    origin: ide.palette,
+                    position: ide.palette.center()
+                };
+            }
         },
         'make a copy\nand pick it up'
     );