Sets the number of columns used for this tree widget, updating the \
        column resizing modes to stretch the first column.
        
        :param      count | <int>

def setColumnCount( self, count ):
        """
        Sets the number of columns used for this tree widget, updating the \
        column resizing modes to stretch the first column.
        
        :param      count | <int>
        """
        super(XColorTreeWidget, self).setColumnCount(count)
        
        header = self.header()
        header.setResizeMode(0, header.Stretch)
        for i in range(1, count):
            header.setResizeMode(i, header.Fixed)