I'm working on a game that uses animated sprites (spritesheets) for characters. Right now I'm using GIMP for them and I already got some good results. However creating all these different sprites for an animation is very tedious work especially when I decide to change the character a little afterwards and have to edit every sprite again (and make sure there are no small mistakes). I always export the image and run the game to check the results. GIMP has a function to run an animation based on switching through layers but there's no zoom-function in the animation window and for specific animation-parts I have to re-arrange the layers all the time.
Is there some software that displays several animations simultaneously (like: window1 shows walking, window2 running,...) and updates those animations while the artist changes pixels on the spritesheet? This would probably speed up things a lot.