Thanks for all the feedback via forum / email / private message
So far, this is on the list:
v - change 'Bold on/off' to 'Bold' (question: should the Bold button also be a toggle, like 'Pencil' ?)
v - gaps appear at cell corners when number pad is opened
v - pressing 'Bold' empties any guesses in the cell
v - when Pencil mode is on, the button shows an 'X', should probably just be 'Pencil' still with green background
v - for -3 ... 3 puzzles (and puzzles from zero), the button number range is incorrect
v - add checkmark when Pencil mode is on
- for large puzzles (12x12) the guesses on the right hand side can spill into the number pad (make pad switchable to the left?)
v - for Sudoku and Killer: explanation box should disappear/become smaller when number pad is opened
v - for Killer: number buttons are too small
v - no-op puzzles need extra operator buttons
v - check puzzle + pad spacing when ads are shown
v - number pad should disappear when printing
- add hover and "press" effects
Ok time to get busy
Edit: marking the items that have been done with a bold
v