Pass through block drag event

src/engine/blocks.js

@@ -288,6 +288,16 @@ class Blocks {
                 newCoordinate: e.newCoordinate
             });
             break;
+        case 'drag':
+            if (optRuntime) {
+                optRuntime.emitBlockDragUpdate(e.isOutside);
+            }
+            break;
+        case 'endDrag':
+            if (optRuntime) {
+                optRuntime.emitBlockDragUpdate(false /* areBlocksOverGui */);
+            }
+            break;
         case 'delete':
             // Don't accept delete events for missing blocks,
             // or shadow blocks being obscured.

src/engine/runtime.js

@@ -379,6 +379,15 @@ class Runtime extends EventEmitter {
         return 'MONITORS_UPDATE';
     }
 
+    /**
+     * Event name for block drag update.
+     * @const {string}
+     */
+    static get BLOCK_DRAG_UPDATE () {
+        return 'BLOCK_DRAG_UPDATE';
+    }
+
+
     /**
      * Event name for reporting that an extension was added.
      * @const {string}
@@ -1387,6 +1396,14 @@ class Runtime extends EventEmitter {
         }
     }
 
+    /**
+     * Emit whether blocks are being dragged over gui
+     * @param {boolean} areBlocksOverGui True if blocks are dragged out of blocks workspace, false otherwise
+     */
+    emitBlockDragUpdate (areBlocksOverGui) {
+        this.emit(Runtime.BLOCK_DRAG_UPDATE, areBlocksOverGui);
+    }
+
     /**
      * Emit value for reporter to show in the blocks.
      * @param {string} blockId ID for the block.

src/virtual-machine.js

@@ -74,6 +74,9 @@ class VirtualMachine extends EventEmitter {
         this.runtime.on(Runtime.MONITORS_UPDATE, monitorList => {
             this.emit(Runtime.MONITORS_UPDATE, monitorList);
         });
+        this.runtime.on(Runtime.BLOCK_DRAG_UPDATE, areBlocksOverGui => {
+            this.emit(Runtime.BLOCK_DRAG_UPDATE, areBlocksOverGui);
+        });
         this.runtime.on(Runtime.EXTENSION_ADDED, blocksInfo => {
             this.emit(Runtime.EXTENSION_ADDED, blocksInfo);
         });