问题
If I have a one SWF movie imported inside of another, how do I make the inner one have a transparent background?
回答1:
SWFs imported will always have transparent background - the Loader object itself doesn't work like, say iFrame in HTML. Unless you have a background in the SWF made up of some graphics, or MovieClips, Sprites, Buttons... whatever else, then you won't see the default backdrop you can see in IDE while working with the FLA file of that SWF.
回答2:
try different BlendModes
来源：https://stackoverflow.com/questions/4148250/make-a-swf-have-a-transparent-background