First step for a GTK version

First step for a GTK version

this version doesn't do much, apart from an "quit" button that seems to work.
Lots of things need to be still changed:
* there is still a lot of calls to X... function in the code
* lots of printf("Debug...") (used those instead of a debugger)
* some X-code has just been commented out, but has not been replaced with the GTK code
...

guess the list is long at the moment ;)