Tom, there's a reason that Tkinter is included with Python - it's probably the most straitforward of the 4 you mentioned. It's dead easy to get running on Win32 and Linux systems (haven't tried on Mac OS, but I hear reports of it being used).
I found GTK to be damn near impossible to install on Windows, after numerous attempts. Maybe if you're building shrink-wrap systems you wouldn't have the issue - just provide an executable and a .dll. wxPython, some people say, feels like C++. That may be a pro or a con. As for QT, great on Linux, difficult or expensive to license on Windows. There'll be an open-source version, but that's a year off by the time PyQt 4 is ready. If you haven't worked with any GUI toolkits before, why not start with Tkinter - concepts like callbacks, threads and events, key to making GUI apps work, are transferable between toolkits. cheers S -- http://mail.python.org/mailman/listinfo/python-list