I use a laptop all of the time, and prefer the mouse input, however, having to select the numbers by clicking on them (the scroll wheel is, of course, not available on a trackpad) always feels a little tedious. Would it not be possible to have the numbers selected by pressing the relevant 1-9 key?
I know that this would only be appropriate on numerical puzzles up to 3x3, but I would guess that it how the majority of players will be using the program...