QScrollbar show scratching on scrolling on any widget

Hi

I m using QtreeWidget ...When Vertical or Horizontal scrollbar come inside the QTreeWidget,
It created gaping ..When I m scrolling the scrollbar it becomes blurring the scrolling area or text inside treeWidget is visible between ScrollBar and TreeWidget and pixel display....It doesnot come as fine Scrolling in QtreeWidget....Which widget function will i use so that wehn scrolling it looks like fine treeWidget....

If anybody know please help me....