Class: DragManager
DragManager
DragManager handles drag & drop events. It registers listeners for mousedown,
touchstart on the target and mousemove, touchmove, mouseup, mouseupoutside,
touchend, touchendoutside on the stage.
By default, draggable widgets will internally handle drag-n-drop and reassigning
the callbacks on their DragManager will break their behaviour. You can prevent
this by using eventBroker.dnd directly without setting widget.draggable to
true (or using widget.makeDraggable()).