background color for qtreeview when checkbox is placed

hi,
I have set background color for QTreeView and the view has QCheckBox also.So in the delegate i have drawn the QCheckbox but the remaining area of the cell where my QCheckbox is placedhas no background color.I understand QRect takes the whole cell and paints the check box but how do i say to paint the remaining are of cell(apart form QCheckBox) with my background color.

thanks,