I could add a 'remap'-feature to the grid tool

- remap(swap) tiles (per drag&drop) and add grid
- save image and additional map-file
- edit image (in what ever you like)
- load image and additional map-file
- removegrid & move tiles to original position

This could help to avoid massive changes to p-rom.
Are you interessted or do you prefer changing p-rom? This could also help to edit auto-animation (the scrambled ones)..