Getting GtkRadiant to run under Ubuntu isn't that easy. First you try to follow the Compiling Howto and in the end you'll recognize that "scons SETUP=0" doesnt work.

Why doesn't it? Cause there are packages missing!
Besides the packages mentioned in the Compiling Howto, following packages are needed too:

• g++
• gcc
• libgl1-mesa-dev
• libglib2.0-dev
• libgtk2.0-dev
• libgtkglext1-dev
• libxml2-dev

And thats it! (If I missed any, please let me know.)

Now you can go on with "install:". ;)