Command Options|Right Click controls Shift Right Click vs Right Click behaviour
Gap seems to be inconsistant. Distance to the EndPoint also plays into which Gap moves.
Unless to there is a clever reason for this, I'd call it a bug
Spliting a Circle creates a big Curve track.
If it just Split the Circle we'd have a track connected to itself.
This would be very confusing to XTrkCad and lead to 'Bad Things' happening.
I doubt Gaps on a Circle would be very meaningfull