One thing I rarely ever do in Java is program anything that requires a desktop UI. If I'm doing any Java programming, it's generally server-side related. Recently that changed when I began working on a Java applet that allows users to upload images (screenshots) in their clipboards directly to the server.
Building the basic applet was pretty straightforward. Even signing the applet (so you can actually query the operating systems clipboard) is pretty straightforward—made even easier once I created an ANT build script.
The applet was progressing nicely, well that's until I tested things on the Mac.