release all keys on blur

hxd/Stage.hl.hx

@@ -150,6 +150,15 @@ class Stage {
 				wasBlurred = false;
 			case Blur:
 				wasBlurred = true;
+				#if hldx
+				// release all keys
+				var ev = new Event(EKeyUp);
+				for( i in 0...@:privateAccess hxd.Key.keyPressed.length )
+					if( hxd.Key.isDown(i) ) {
+						ev.keyCode = i;
+						event(ev);
+					}
+				#end
 			default:
 			}
 		case MouseDown: