null true if (!this._draggableStarted) { this._draggableStarted = true; try { let tmp = {}; Components.utils.import("resource://gre/modules/WindowDraggingUtils.jsm", tmp); let draghandle = new tmp.WindowDraggingElement(this); draghandle.mouseDownCheck = function () { return this._dragBindingAlive; }; } catch (e) {} }