This week's giveaway is in the EJB and other Java EE Technologies forum. We're giving away four copies of EJB 3 in Action and have Debu Panda, Reza Rahman, Ryan Cuprak, and Michael Remijan on-line! See this thread for details.
The only way this might be possible is to implement WindowListener on your JFrame and then in the windowMaximized(WindowEvent w) method adjust the verticle of your JFrame to not change. The problem with this is you are going to see the JFrame maximize in both directions and then see the height change after that.