Hi there 
actually I had some ideas to create an alternative 2D view of the palette (and tiles), so we could re-arrange colors (and tiles) moving then around. (Keeping indexes fixed.) I guess the “swapping” feature is an easy workaround to replace the content where the palette entries/tiles are dropped.
Still have to think about:
- How should be the exact UI (how to switch between both views, how to “paint” in the 2D view)
- How should palette groups be handled in both cases (linear and 2D), maybe only visible on linear (as in a 2D grid it’s easier to make groups)
- How to store the 2D information (maybe a cel chunk)
Basically the 2D view would be quite similar to an editor, but:
- Clicking a pixel/color/tile would drag&drop the pixel/color/tile (we should be able to repeat the same color/tile in several positions too)
- The editable surface will be a hidden cel separated from the sprite, that shares the same palette/tileset that the current sprite layer.