Add Redo, Undo, and Save buttons to favorite toolbox
Everytime I need to double tap to have the "redo/undo" show up at the corner, I have no problem with it. But could you really add the possibility/option to have redo/undo/save buttons added to the favorite toolbox? I am so sure this will save a lot of time for user from "double tapping to access the redo/undo" and "tap navigation pan to show, tap save, tap back the drawing area".
This is the only MS Store APP that I have purchased in my life, make me proud :)