new gesture: holding the shift-key when dragging extracts a single command from a stack of blocks

HISTORY.md

@@ -2,10 +2,11 @@
 
 ## in development:
 * **New Features:**
+    * new gesture: holding the shift-key when dragging extracts a single command from a stack of blocks
+    * new "extract" single command block context menu option
     * added "pie chart" option to PLOT command in the frequency distribution analysis library
     * added getProjectXML() method to the API
     * new noCloud flag that disables cloud access, thanks, Bernat
-    * new "extract" single command block context menu option
 * **Documentation Updates:**
     * API update
 * **Notable Fixes:**
@@ -20,6 +21,7 @@
 * blocks: refactored userDestroyJustThis
 * blocks: un-hid "extract" menu-option
 * morphic: create drop-shadows just in time
+* blocks: holding the shift-key when dragging extracts a single command from a stack of blocks
 
 ### 2020-10-21
 * gui: wait until all costumes have loaded before auto-triggering the green-flag event 

src/blocks.js

@@ -5195,6 +5195,14 @@ CommandBlockMorph.prototype.snap = function (hand) {
 };
 
 CommandBlockMorph.prototype.prepareToBeGrabbed = function (handMorph) {
+    // check whether the shift-key is held down and if I can be "extracted"
+    if (handMorph && handMorph.world.currentKey === 16 && this.nextBlock()) {
+        this.extract(); // NOTE: no infinite recursion, because extract()
+                        // doesn't call this again with a hand
+        handMorph.grabOrigin.action = 'extract'; // ???
+        return;
+    }
+
     var oldPos = this.position();
 
     if (this.parent instanceof RingReporterSlotMorph) {