clicking in the page control area does not advance the slider by one page but moves to the clicked position instead.

acc. to QScrollBar docs it should:
c. The page control is the area over which the slider is dragged (the scroll bar's background). Clicking here moves the scroll bar towards the click by one "page". This value is usually the same as the length of the slider.

and that's how i really expect it to work. The current behavior does not allow browsing through long documents without missing lines, because you may not be able even by very carefully clicking immediately besides the thumb to scroll at most 1 page.

actually this severely nags me in QtCreators source editor and program output window (etc...).
It can be fixed somehow because e.g. in QtCreators help viewer scrollbars work as expcted.