It used to be possible to type stuff like pitch*0.2 or stuff like pitch+roll (like on this green motor) in the input field in the part properties tab in the designer.
Now this is only possible by tinkering the hidden properties.
It wasn’t possible for control surfaces before (unless you manually add a new input controller in hidden properties) but I think it should also be possible for those.
@Pedro nope, still have to go to sandbox and enable tinker panel and restart the designer.