Hi everyone, and thanks for giving us the opportunity to make suggestion for VBA-M, an already great emulator
One of my hobbies is making screenshot maps of console games, a process which usually requires taking a lot of screen captures of a level, usually several times over to capture different parts like the foreground, the background, the sprites, etc.
One of the biggest problem I've encountered while mapping is that, when removing a layer like, say, the background one, it is often replaced with the color black (RGB 0,0,0) (but not always, since some games seem to use their own colors for a sort of blue-screen effect). Anyway, the problem is that black is a color often used both in sprites and in some games' actual level graphics. It therefore becomes very hard to isolate a game's specific layer; if removing the background left a unique, user-defined color in its place, you could easily remove only that color and be left with clean screenshots that could then be assembled and pasted over a similar collage of the background.
Me and a few mapping friends have been lucky to see similar options included in other emulators (specifically Gens and FCEUX) and I thus humbly suggest a similar option if it is at all feasible by VBA-M's coders. It wouldn't even need to be fancy; both of my example simply read a user-defined RGB value in the emulator's config file.
Anyway, I don't want to sound like I'm demanding anything. If you ever consider such a thing, I and others would be very grateful. Thanks for reading