QPlastiqueStyle and QTreeView Scrollbar

Hello everyone

I'm using QPlastiqueStyle in my application, but I have a problem with the scrollbars of QTreeView, I cant click on the scrollbar on the side of the tree and just drag it up an down, it does not work, I can either use the mouse wheel (click on an item in the tree, and then use the mouse wheel), or click on the up/down buttons of the scrollbar.

This only happened once I used this style, is this the way it normally works?

I've tried it on Windows XP

Thanks for your help!