Committed `whenUndockedOnce()` and `whenDockedOnce...

# tornadofx

[edvin]

Committed whenUndockedOnce() and whenDockedOnce() 🙂

[carlw]

What would you think about something like this?

whenUndocked().once() or once().whenUndocked()?

That way, you are able to bring it into general Boolean binds and avoid creating an ever-expanding list of functions for each condition like "whenDisabledOnce()".

[edvin]

I'm not exactly sure how you'd implement something like that, and I think it's a lot less discoverable, especially for new users. There really is just a finite number of these things. I know we're missing some of them now, will add all I can find 🙂