Add no_ui=TRUE to XB's field type definition

wim leers → made their first commit to this issue’s fork.

This looks great, but if there's time, what do you think of adding a test for this? Mostly just to prevent this line from accidentally getting deleted in some future MR.

I don't see how this could accidentally get deleted when the comments literally specify the reason for it being there? A test for this is wasted time IMHO. 😇

I concur with Wim on this one!