[QTWebkit] Hide the scroll bar not works

Hi all, Recently, I want to hide the scroll bar in webkit, then I use currentTab()->page()->mainFrame()->setScrollBarPolicy(Qt::Vertical,Qt:crollBarAlwaysOff); The scroll bar disappear, but even I enable the spatial navigation, I cannot scroll down the page by mouse wheel…… Actually, I want hide the bar, not disable the bar. The definition of ScrollBarAlwaysOff is not show the scroll bar, but it means hide the bar or disable the bar? I have no idea to hide the scroll bar ACTUALLY.