As for $d021: No, bad idea, there's no standard bitmap editor around that supports this
And sorry, that is just dumb beyond belief
I've understood that you think competition between groups in the scene is a bad thing,
and I can certainly see arguments to support such a claim, but it's not like there is a lack of arguments for competition between groups either. Failing to recognize that other viewpoints than your own may be supported by valid arguments just makes you come across as either arrogant, ignorant or a combination thereof.
I’d have thought it would be reasonably straight forward for a good coder to code something that allows for multi colour bitmaps (drawn using existing bitmap editors) to be loaded into memory, with an editor that allows for the sprites in the left and right borders to be edited (drawn). The option to save a RUNable image (for compo use) would be helpful too.
Creating a similar editor that allows for upper and lower borders to be used I guess throws up more issues, as some artists might want to position the sprites in different locations along the upper and lower border area. Although an option to side the spites left or right within the upper and lower border might be one solution.
For most artists, using Photoshop, some imagination, and knowing a good coder is the best option.