I'd like to throw a few more on the list, since we're on the topic (literally).
1) Currently when the window is resized, the sprite is resized in the preview window, leading to a Preview Scale of 1 not actually being a 1:1 relationship the moment the window is resized.
2) A more granular option to control what tints or otherwise shift from palette A to palette B would be nice.
3) *Bug* When I simulate an animation that involves breaking, the simulation temporarily changes to Preview Scale 1 (but the slider/value does not change), regardless of my currently set Preview Scale. At simulation end it reverts.
4) What exactly does the reverse toggle at the bottom of the Simulate/Render section do? It doesn't appear to do either of the things I was expecting (reversing the animation or reversing the layer)
5) An option to make a layer orbit around center with a radius, speed, and inclination and/or major/minor axes would create a lot of new options very fast.
6) Blur is nice but it appears to shrink the sprite rather than spreading it as seen on the test sprite included, and it would be helpful to have some sort of method to decide the level of blur.
I'm having a lot of fun with the tool myself so far and have had some good uses out of it already. Cheers!