Toggle button in toolbar

I see it's possible to set an action function for custom toolbar icons, but how to I make it toggle on and off?

It seems the `getState()` function is in charge of what's active and what's not. Is there a way to hook into that? I have a toggle button that turns on and off custom code and I need the button to be in an active state when enabled.

Thank you

The issue names no file or test. Start by reviewing the custom toolbar action and getState() documentation or implementation, then determine whether the supported toggle behavior is documented; done means the active-state hook and a usage example are clear to users.

Written by the indexing model from the issue text.