Sets the color that for the progress bar for this item.
        
        :param      color | <QColor>

def setProgressColor( self, color ):
        """
        Sets the color that for the progress bar for this item.
        
        :param      color | <QColor>
        """
        self._progressColor = QColor(color)
        self.setAlternateProgressColor(self._progressColor.darker(110))