Allow customization of the S Pen gestures, add toggle-swipes
I don't really feel a need for the Undo and Redo swipes (readily tappable in bottom toolbar). But swipes that could toggle highlighter or toggle selector (with another swipe in the same direction reverting to pen) could be handy. And the ability to assign the swipe function to whichever direction you like.
(great app, btw!)