It's pretty hard to test your app because of the severe limitations on texture size. If you must put a limitation on the program just add a water mark when users try to save a texture out but allow users to open any file size they want. While I'm curious about the program, I don't feel like spending time making 256…
^^ 100% in agreement on the process this sort of thing takes ages and you need to iterate - more time here == less time fixing mistakes for that example I'd want the smallest granularity to represent something along the lines of a house rather than a door/window/wall section etc. that could be actor/level…