I was trying to make a simple GIF capturing app, but I needed to make a hole/transparent space in a JFrame based on a JPanel. I tried many things, from per-pixel transparency (only works with undecorated windows...), custom shapes (again, undecorated windows only), etc...
In .NET Framework, it's as simple as setting the TransparencyKey color of the form, and setting the panel's background color to that color.
I'm wondering if this is possible....