Feature to allow ButtonGroup to be unset by user

[metalgearsloth]

trafficstars

1. Make ButtonGroup with IsNoneSetAllowed True.
2. Try to press pressed button.
3. Watch as it doesn't work.

Requires you to click another button as a workaround atm.

[PJB3005]

This is by design, they're intended for stuff like radio buttons where this generally isn't the paradigm. That said it might be a useful feature to add.