Hi Chris,
I just tried with LCG 99 and widget as Phil did and I don’t see the behaviour you describe (the reported cursor position coincides with the actual position). This is with Chromium.
Is this something you can reproduce outside of SWAN?
EDIT: I now read you don’t have this behaviour in a normal notebook. It’s definitely not something we are aware as a bug and it’s weird that we can’t reproduce consistently.