KeyboardShortcuts | Control Virt-A-Mate commands with the keyboard | Keyboard library

Try this

You pass protocol to the togglePopover instead of an instance. You can pass self.

There are several approaches, but assuming you know all the "command" strings and what they map to, you can take an enum approach:

When the user "presses two keys", it's impossible for both key presses to happen simultaneously, so one of the key presses will necessarily be detected before the other. Probably the best approach here is to ensure one of the keys (say B) doesn't have it's own functionality. That way the user will learn to always press B first, then A while B is held down (this is the way we type, using modifier keys such as SHIFT and CTRL).

If you really want both keys to have their own functionality, but different functionality when both are pressed "at the same time", then your only option is to implement a delay in handling the press of a single key, waiting to see if the other key is pressed before that delay expires. This, of course, comes at the expense of responsiveness.

Here's an implementation of that, using a short (25ms) PauseTransition for the delay. (I also changed to use an ObservableSet, which cleans up some of the logic.)