Inset focusring with curls: Xojo or NSTableViewMBS?

I love finding truly weird bugs. I made a popover window with an NSTableviewMBS. The tableview has a focusring which isn’t showing when I select a row:

After adding a searchfield and I tab from the searchfield to the NSTableviewMBS I get the focusring. But it’s inside of the tableview with some lovely curls:

Setting the focusring to NSScrollViewMBS.NSFocusRingTypeNone removes the problem. Is this a Xojo or a plugin problem?