Oddly enough, your latest += margin snippet gives me a negative margin integer, and the buttons are off the frame. I think I just have a GUI setup thats too convoluted -- boxes insides panels inside frames, each having various layouts, etc. In time, I must try to clean it up.
I am so happy with how this worked out, though, I'm interested in how far one can take this glassPane technique. Is it possible to specify a second component and place it absolutely on the same glasspane? I don't get the impression that multiple glasspanes are possible, is that so?