I found that the [embed] tag has many undocumented features (and WHY ... WHY are they not documented?! and IS there any place where it is all thoroughly documented? Well, the one in the Flex documentation isn't really that helpful)
So you can embed PNGs in a compressed way like JPGs with compression=true and quality=70 i.e. to save a transparent PNG with JPEG compression.
BUT when I do that, the alpha seems to not get premultiplied, it doesn't behave like when I don't compress it. The shadows aren't dark anymore but almost lighten the areas up. When not using compression & quality, the shadow areas look like they're supposed to.
When using a PNG compressed by the Flash IDE, it works.
So, is there ANOTHER undocumented embed-feature which lets you control if the alpha-channel gets premultiplied or not?
That would really help in some cases.
Right now I'm still using the Flash IDE for that, but it would be nice to know if there is a way to make it work merely by Flex EMBED tags.