'Command-q': Quit to MacOS (all your work and settings are auto-saved).
These hotkey actions are only available thru the keyboard, and have no clickable buttons
'Esc': Bring up the main menu (where you can find the manual etc).
'F15' or 'Help' or 'Command-Space': Bring up a 'Quick Help' dialog about whatever is underneath the mouse pointer.
These hotkey actions work on the last window you used that action on
'F9': Toggle between fullscreen and normal mode.
'F10': Rotate the window contents.
These hotkey actions work on the target picture
'Command-z' or 'F1': Undo the last effect/operation made on that picture.
'Control-*': View the picture (all layers) in fullscreen mode. Repeat, or just click with the mouse, to go back.
Modifiers
'Shift', 'Control', 'Alt' ('Option') and 'Command': Hold down, in any combination, when painting or mask painting (and in the tool selector: first click selects, second click brings up settings dialog) to simulate up to 16 mouse buttons.
