Sets the total value for the sub progress bar.
        
        :param      amount | <int>

def setSubTotal( self, amount ):
        """
        Sets the total value for the sub progress bar.
        
        :param      amount | <int>
        """
        self._subProgressBar.setValue(0)
        self._subProgressBar.setMaximum(amount)
        if amount:
            self.setShowSubProgress(True)