simgunz added a comment.
The artifacts are caused by the fact that the highlight rectangle is drawn "inside the 'limits' paint region". When an highlight is only partially shown because it is at the top/bottom edges of the window, the border rectangle is drawn across the highlight (correctly). If the page is scrolled showing now the full highlight, the rectangle is drawn again around the whole highlight, but the previous rectangle is still there resulting in a horizontal line across the highlight. This can be reproduced by slowly scrolling the page while an highlight is on the top/bottom border. REPOSITORY R223 Okular REVISION DETAIL https://phabricator.kde.org/D7662 To: sander, #okular Cc: simgunz, cfeck, aacid, ngraham, michaelweghorn