Hi,
I use the drawing area quite a lot to make sure I'm actually remembering kanji properly. It's very useful.
What I do find however is , it isn't very responsive to double taps to erase. ( iPodTouch 3 gen, iOS4.2.1, FCD2.7.1) I've tried many variations of speed etc. and it can be very hit and miss.
I wonder if you could consider an erase icon as well. Maybe user configurable to minimise on screen clutter
or is a Newton-like up-down-up-down-up-down erase gesture available?
or an erase tool, to rub out only the mistake, if you are expanding the capabilities of the drawing area?
Thanks