public  void actionPerformed(ActionEvent e) 
{
      int lead = list.getLeadSelectionIndex();
      int max = list.getModel().getSize() - 1;
      DefaultListSelectionModel selModel = (DefaultListSelectionModel)list.getSelectionModel();
      String command = e.getActionCommand();
      // Do nothing if list is empty
      if (max == -1)
        return;
      if (command.equals("selectNextRow"))
        {
          selectNextIndex();
        }
      else if (command.equals("selectPreviousRow"))
        {
          selectPreviousIndex();
        }
      else if (command.equals("clearSelection"))
        {
          list.clearSelection();
        }
      else if (command.equals("selectAll"))
        {
          list.setSelectionInterval(0, max);
          // this next line is to restore the lead selection index to the old
          // position, because select-all should not change the lead index
          list.addSelectionInterval(lead, lead);
        }
      else if (command.equals("selectLastRow"))
        {
          list.setSelectedIndex(list.getModel().getSize() - 1); 
        }
      else if (command.equals("selectLastRowChangeLead"))
        {
          selModel.moveLeadSelectionIndex(list.getModel().getSize() - 1);
        }
      else if (command.equals("scrollDownExtendSelection"))
        {
          int target;
          if (lead == list.getLastVisibleIndex())
            {
              target = Math.min
                (max, lead + (list.getLastVisibleIndex() -
                    list.getFirstVisibleIndex() + 1));
            }
          else
            target = list.getLastVisibleIndex();
          selModel.setLeadSelectionIndex(target);
        }
      else if (command.equals("scrollDownChangeLead"))
        {
          int target;
          if (lead == list.getLastVisibleIndex())
            {
              target = Math.min
                (max, lead + (list.getLastVisibleIndex() -
                    list.getFirstVisibleIndex() + 1));
            }
          else
            target = list.getLastVisibleIndex();
          selModel.moveLeadSelectionIndex(target);
        }
      else if (command.equals("scrollUpExtendSelection"))
        {
          int target;
          if (lead == list.getFirstVisibleIndex())
            {
              target = Math.max 
                (0, lead - (list.getLastVisibleIndex() - 
                    list.getFirstVisibleIndex() + 1));
            }
          else
            target = list.getFirstVisibleIndex();
          selModel.setLeadSelectionIndex(target);
        }
      else if (command.equals("scrollUpChangeLead"))
        {
          int target;
          if (lead == list.getFirstVisibleIndex())
            {
              target = Math.max 
                (0, lead - (list.getLastVisibleIndex() - 
                    list.getFirstVisibleIndex() + 1));
            }
          else
            target = list.getFirstVisibleIndex();
          selModel.moveLeadSelectionIndex(target);
        }
      else if (command.equals("selectNextRowExtendSelection"))
        {
          selModel.setLeadSelectionIndex(Math.min(lead + 1,max));
        }
      else if (command.equals("selectFirstRow"))
        {
          list.setSelectedIndex(0);
        }
      else if (command.equals("selectFirstRowChangeLead"))
          {
            selModel.moveLeadSelectionIndex(0);
          }
      else if (command.equals("selectFirstRowExtendSelection"))
        {
          selModel.setLeadSelectionIndex(0);
        }
      else if (command.equals("selectPreviousRowExtendSelection"))
        {
          selModel.setLeadSelectionIndex(Math.max(0,lead - 1));
        }
      else if (command.equals("scrollUp"))
        {
          int target;
          if (lead == list.getFirstVisibleIndex())
            {
              target = Math.max 
                (0, lead - (list.getLastVisibleIndex() - 
                    list.getFirstVisibleIndex() + 1));
            }
          else
            target = list.getFirstVisibleIndex();
          list.setSelectedIndex(target);          
        }
      else if (command.equals("selectLastRowExtendSelection"))
        {
          selModel.setLeadSelectionIndex(list.getModel().getSize() - 1);
        }
      else if (command.equals("scrollDown"))
        {
          int target;
          if (lead == list.getLastVisibleIndex())
            {
              target = Math.min
                (max, lead + (list.getLastVisibleIndex() -
                    list.getFirstVisibleIndex() + 1));
            }
          else
            target = list.getLastVisibleIndex();
          list.setSelectedIndex(target);
        }
      else if (command.equals("selectNextRowChangeLead"))
          {
            if (selModel.getSelectionMode() != ListSelectionModel.MULTIPLE_INTERVAL_SELECTION)
              selectNextIndex();
            else
              {
                selModel.moveLeadSelectionIndex(Math.min(max, lead + 1));
              }
          }
      else if (command.equals("selectPreviousRowChangeLead"))
        {
          if (selModel.getSelectionMode() != ListSelectionModel.MULTIPLE_INTERVAL_SELECTION)
            selectPreviousIndex();
          else
            {
              selModel.moveLeadSelectionIndex(Math.max(0, lead - 1));
            }
        }      
      else if (command.equals("addToSelection"))
        {
          list.addSelectionInterval(lead, lead);
        }
      else if (command.equals("extendTo"))
        {
          selModel.setSelectionInterval(selModel.getAnchorSelectionIndex(),
                                        lead);
        }
      else if (command.equals("toggleAndAnchor"))
        {
          if (!list.isSelectedIndex(lead))
            list.addSelectionInterval(lead, lead);
          else
            list.removeSelectionInterval(lead, lead);
          selModel.setAnchorSelectionIndex(lead);
        }
      else 
        {
          // DEBUG: uncomment the following line to print out 
          // key bindings that aren't implemented yet
          // System.out.println ("not implemented: "+e.getActionCommand());
        }
      list.ensureIndexIsVisible(list.getLeadSelectionIndex());
}