Flash-將MovieClip移到最高層

container.setChildIndex(container.getChildAt(1), 0);

Parameters
child: DisplayObject — The child DisplayObject instance for which you want to change the index number.
index:int — The resulting index number for the child display object.

搭配numChildren就可以把MovieClip丟到最上層去
setChildIndex(myMC,numChildren – 1);