Dismisses the hovered item when the tree is exited.
        
        :param      event | <QEvent>

def leaveEvent( self, event ):
        """
        Dismisses the hovered item when the tree is exited.
        
        :param      event | <QEvent>
        """
        hitem = self.hoveredItem()
        hcol  = self.hoveredColumn()
        
        if ( hitem != None ):
            self._hoveredItem   = None
            self._hoveredColumn = -1
            
            rect = self.visualItemRect(hitem)
            rect.setWidth(self.viewport().width())
            self.viewport().update(rect)
        
        super(XTreeWidget, self).leaveEvent(event)