Artefacts in composition mode

I keep getting what I can only describe as artefacts in composition mode where after the scroll bar goes away there are still broken vertical lines where the scroll bar was. This also happens when the toolbar at the bottom goes away, there are broken horizontal lines just at the top of where the toolbar was.

I find these very distracting and find that i don’t use composition mode because of it.

Does anyone else get this?

Is this a bug in Scrivener? Or my machine?

Any thoughts?