Scrolls the parts to offset the scrolling amount.
        
        :param      amount | <int>

def scrollParts( self, amount ):
        """
        Scrolls the parts to offset the scrolling amount.
        
        :param      amount | <int>
        """
        change = self._scrollAmount - amount
        self._partsWidget.scroll(change, 0)
        self._scrollAmount = amount