This one is from the Mac OS X list, from a posting by Douglas Davidson: (I might put in some CocoaSampleCode later if I get the time)

Here’s the procedure I was using to get a fixed-height drawer:

• don’t try to set the drawer’s minContentSize;
• in the parent window’s delegate, implement windowDidResize: and in that method set the drawer’s trailing offset based on the parent window’s frame size (take the height and subtract some fixed constant);
• in the parent window’s delegate, implement windowWillResize:toSize: to constrain the parent window’s height so that there is sufficient room for the drawer.

– JensBaumeister