When I hide the toolbar in the Finder, the border line between the tabs and the white window area is often thicker than normal. When I unhide and hide the toolbar again, it returns to normal. When I then open a new tab again, it returns to be too thick.
Searched for this with the forum search function and found nothing, sorry if this is a duplicate!
Using 10.9.2 and 1.5.22.
Line too thick: