if (selected > 0) {
if (selected != -1) {
      public void actionPerformed(ActionEvent e) {	int selected = m_ClassCombo.getSelectedIndex();	if (selected > 0) {	  boolean isNominal = m_Instances.attribute(selected).isNominal();	  m_OutputTFPosBut.setEnabled(isNominal);	  m_OutputConfusionBut.setEnabled(isNominal);		}      }