The event can only bubble up through the display list if the object that dispatched the event is a DisplayObject (or an ancestor of DisplayObject, such as a Sprite or MovieClip) so that it can be in the display list AND it is added to the display list at the time of the event dispatch.

唔係你係類面 new 個 instance ，佢就識玩 bubble

而係 addChild 落個 displaylist 到先識玩 bubbling

new object 個個你就要一層層咁自己 dispatch~