Thank you for this beautiful app! Works very well! Sometimes it still crashes - couldnt figure out why... (iOS 9.1 - iPad 3) I bought the drawing add-on - works fine! BUT could you please improve the undo-function: When you are drawing something, for example several lines, and you want to delete the last line you hit the undo button aaand... - your whole drawing is gone. All of the lines, not only the last one. That is really annoying. And a rubber in addition would be awesome!