A while back I read (before I lost it) a great book called GUI Bloopers which was full of examples of bad GUI design but also full of useful tidbits like Don't call something a Dialog one minute and a Popup the next.

What top tips would you give for designing/documenting a GUI? It would be particularly useful to hear about widgets you designed to cram readable information into as little screen real-estate as possible.

I'm going to roll this off with one of my own: avoid trees (e.g. Swing's JTree) unless you really can't avoid it, or have a unbounded hierarchy of stuff. I have found that users don't find them intuitive and they are hard to navigate and filter.

PS. I think this question differs from this one as I'm asking for generalist tips