Scrollbar marks painted at the wrong position

Setting: macOS, MacBook with touchpad, auto-hiding of scrollbars on (the default).

1. open a file that would fit on screen (e.g. dummy main.cpp)
2. make the window smaller, so the file is scrollable - QtC paints the cursor marker in the scrollbar area
3. make the window larger, so the file no longer is scrollable - QtC continues painting the cursor marker, at the previous x-position, which might now be in the middle of the window

See attached video.