GTKradiant is a community driven project. It lives from dedicated people putting time and effort into coding and testing. If you want to report bugs or get involved with the project check the GitHub repository.
Also feel free to join the official GTKradiant channel on QuakeNet IRC to discuss potential bugs and features.
In the latest build, sometimes (not always) whenever I try to open up a dialog box, it appears behind the editor, forcing you to have to minimize the editor or restore it down and drag it away. In addition, sometimes when I try to open up a window, the editor stays in front, so I also have to minimize it if I want to go to another window. I haven't been able to figure out what specifically causes this; it happens sporadically. Running Windows 7 Home Premium SP1.
Are you using the floating window layout? It's a known issue most likely with the GIMP toolkit so it won't be an easy fix, there have been some workarounds being investigated. For now, it's best to avoid using the floating window layout.
The "Floating Z Window" option is disabled in the layout preferences. I also used a fixed layout for the workspace: https://dl.dropbox.com/u/27277779/gt...tlayout_ql.jpg