Another way is to use a deceptive outline, it works okish with transparencies, see:
Notice you don't have to worry about overgoing the boundaris, because it actually makes your image more interactive with the background. If I were to inverse it, it would give me the following effect:
And naturally this'd mean that the green, with the inversed outgrowth would be:
In any case, if glow doesn't work you can use a similar feat.
Turin