Can't shade some windows

[enigma_0Z]

It seems that some windows (such as wine windows, firefox downloads, etc) can't be shaded. I could shade any window in Beryl or even kwin, can't I in compiz?

Is there a configuration option that I missed, or does this belong in "Feature Requests"

[Forlong]

I can shade the Downloads window of Firefox just fine (don't have wine installed, so I can't test).