One to add to the pot: Bluefish. It's mostly aimed at HTML editing but is a general editor.
One criteria for me is that I need to be able to open remote files via SMB under Gnome (Ubuntu) and that unfortunately rules out a lot of GUI editors. A replacement for UltraEdit would certainly be great news; I have previously got it working under Wine but later versions don't seem to work (I don't recall how they fail now).