Thanks a lot. I do consider pull to save the primary action. Double tap or shake gives you the menu, but I agree this can be simpler. It would pain me to put instructions in the app though...
The "real" problem that I perceived is the double-tap, and I have debugged my interaction a bit more.
What it looks like is that the triple-equal sign is a bit too small for my fat fingers. OTOH you do not want to waste the drawing space too much...
My thought would be: take a rectangle of 2x size the current triple-equal sign action area, then try to both use the drawing mechanism there, as well as to track the doubleclick-like events there - and if one happens, then undo the last drawing event (which was a part of the click, anyway).
I think this should make it easier for fatfingered people to deal with it :) And the translucent advertisement upon the swipe should take care of education, I think.