writing a GUI for an app running under Linux

Hi everyone

I know this not necessarily the best newsgroup to ask that sort of question but please be nice ;-) as I am not too sure where to start with this problem. I use c++ for my work but always write applications that didn't need GUI. And know there's a project for which I'd need to have one. I looked around on the net and it's really incredible to see that there's nothing really clearly written about the subject.

The OS that I use is Linux and i already know that I can use things like Qt, gtk to quickly develop GUI. The problem is that I need the interface to have a certain look (for those who know those app like Shake or Softimage... or some other fancy graphic app like Mojo World ... )

I just try to find a good document somewhere (webpage, book) that explains me how to do that. I am really confused as exactly what motif somewhere how it works and eventually how I can develop my own widgets (basically I'd be happy if I could only open a window with a button in it ;-)

Thanks a lot everyone for reading and for your help

Mark