This is just a minor inconvenience, but it would be nice if when the mouse exited the game window, any pop up text due to mousing over certain objects could disappear.
One thing I would like to see added is a toggle option to automatically move on to the next stage once you complete the current one. This would be very useful for the early levels after resets.
I spent more time trying to get to the "gloat zone" than it took me to kill the boss. (you will know about the gloat zone after you beat it) If not, jump left of the "medium levels" arrow.
The auto-progression feature is available after your first reset, by using the settings menu or pressing "G" on your keyboard.