First off I am no expert [I'm not even good, in fact I'm rather bad] at this process, so I am sure there are many better ways to do things.
I normally use mock to test my own little projects.
Gpaint-2 would not build in mock until I added in the gettext rpm(s) I did not try it without the devel. Less is better though.... The joy of finding / eliminating dependencies / requirements
Also, I could not install the rpm due to a dependency with gnome-print, once I changed that around I could install the application. I disabled the gnome-print requirement and it built and installed fine but no printing, no menu.
So, from dumping the ./configure file and scanning through it I added lignomeprint22, libgnomeprintui22 and libgnomeprintui22-devel and that seemed to work, whether all are needed I don't know.
For the no menu entry, I changed the group to Interface/X and edited you gpaint-2.desktop file and added
and a MimieType for giggles to see if it would work [it did]
Did a : desktop-file-validate gpaint-2.desktop [which was fine]
Then rebuilt - passed through mock and it installed perfectly under Applications / Graphics.
Also, the rpmlint and all rpms were clean as clean.
To add the fc6 extension I normally just have an entry as:
%define dist .fc6
I'm sure there is more formal and better way to accomplish this as well.
I never really thought about it before, I'm sure Firewing1 would have the answer.