Keyboard Shortcut: Invoke functions when multiple keys are pressed

This object can invoke functions when multiple keys are pressed.

It can register event handler functions to be called when a sequence of one or more keys is pressed.

The key sequence is defined by a string with the names of the keys, which can be letters, digits, symbols or qualifier keys like Ctrl, Alt and Shift.

The registered callback handler function may also be called periodically while the defined key sequence is still being pressed.