registerModifierActions

Registers actions such that actions can be selected while holding (combinations of) modifier keys.

All combinations of modifier keys are registered for events. Additionally, the captionModifier function is invoked every time the user presses or releases any modifier key, even while holding other modifier keys.

Events are also registered for pressing the Enter key (with or without modifier keys) to invoke the action that is currently highlighted, and for pressing one of the numbers 1-9 (with or without modifier keys) to invoke the action at that index in the popup.

Parameters