Neither azpainter not mtpaint are suckless. I don't really consider GTK to be suckless (unless it is), for mtpaint And I'm looking at wc -l of all src/ mlk/ files and it's A LOOOOT of lines.
I used Tux in the past.. it does SOME very limited jobs, done. not sure if it can be used for banners and stuff alike that which I'll need to do in the future