I actually place some enemies in the player's way to aid with the movement; the special moves can be chained if you hit enemies with them so there are some enemies that are intended to work as links between attacks in the air. I know I should reserve things like this to late levels, but since the gameplay still isn't finalized and I need to make new levels for every demo, I like to put in a bit of everything. I'll try to make the levels easier to approach in the future, at least the early ones.
About the fullscreen issue, that's odd. I don't think anyone has reported that before, but I'll look into it if I can reproduce it on some system.