Lazarus Project: Cross-platform Delphi
I made a pretty good living for several years as a Delphi guru; if I had to go back to GUI-programming hell, I would want to use Delphi, or something damned close.
Lazarus looks like it might fit the bill (but they need lots of help on their website!) Lazarus is the foundational tool for the newly-released CBTracker, an open-source checkbook manager.