document [45]s suspend/resume by moving the mouse.
document [45]s key stroke commands.
fix sudoku left/right button for menu mixup.
document (existence of) [45]s score files
[should we also document their format?]
document [45]s mouse warping limitation bug/feature.
[TODO? uniform mouse button names: right now we use both
 'button 1' and 'left button' for the same thing.]