Some bugs:
1) When I select "generate palette then pick based on delta", and I use two rows, then tiles with low delta to black tiles, will be match with row 4.
Same behavior with "pick tile row based on delta"
2) After quantization, color sliders not updated.
3) Riemesha instead of Riemersma, and attrabutes instead of attributes (TileMap Actions).
4) TileMap Actions -> Remove tiles after 0 will make big error

There is no option -> generate plain tilemap (0,1,2,3)... So, if I made mistake, I need to restart program.
Another info: now if I select quantization 30 colors based on HUE, Denis Lee, RGB, result for UMK3 select screen will be much worse than previous version of your program.