Tileset spacing

Hello! First of all thank you for Pyxel - it's amaaaazing. Best software purchase in a long time!

One thing that would be super useful to me is to be able to slightly space out the tiles in the tileset window. You can see my problem in the picture below:



I have a bunch of similar tiles with thin borders, and it's very difficult to tell which border sits on which tile at a glance - at least while operating at a zoom level where I can still see the entire set. If the grid was displayed with a few pixels of grey space between each tile, then tile selection would become a lot easier. 

Thanks again!