public DescPropPopup() {
      super("Descriptor Properties");
      v = new JCheckBoxMenuItem("Valid");
      v.addActionListener(new ValidAction());
      p = new JCheckBoxMenuItem("Propagating");
      p.addActionListener(new PropAction());
      delete = new JMenuItem("Delete");
      delete.addActionListener(new DeleteAction());
      duplicate = new JMenuItem("Duplicate");
      duplicate.addActionListener(new DuplicateAction());
      interp = new JMenuItem("Interpolate...");
      interp.addActionListener(new InterpAction());
      interpToMark = new JMenu("Interpolate to Mark");
      interpToMark.setEnabled(false);
      itmAction = new InterpToMarkAction();
      shift = new JMenuItem("Shift...");
      shift.addActionListener(new ShiftAction());
      shiftToMark = new JMenu("Shift to Mark");
      shiftToMark.setEnabled(false);
      stmAction = new ShiftToMarkAction();

      occlusions = new JMenuItem("Occlusions...");
      occAction = new OccAction();
      occlusions.addActionListener(occAction);
      occSeparator = new JSeparator();

      wrt = new JCheckBoxMenuItem("Display with Respect To", false);
      wrt.addActionListener(new WithRespectToAction());

      add(occlusions);
      add(occSeparator);
      add(v);
      add(p);
      add(occSeparator);
      add(delete);
      add(duplicate);
      add(occSeparator);
      add(interp);
      add(interpToMark);
      add(occSeparator);
      add(shift);
      add(shiftToMark);
      add(occSeparator);
      add(wrt);
    }
    public void show(Component invoker, int x, int y) {
      ViperViewMediator mediator = getMediator();
      Point pnt = new Point(x, y);
      EnhancedTable tab = getTable();
      int row = tab.rowAtPoint(pnt);
      desc = getCurrentModel().getDescriptorAtRow(row);
      int col = tab.columnAtPoint(pnt);
      Object cellValue = tab.getValueAt(row, col);
      if (cellValue instanceof Attribute) {
        attr = (Attribute) cellValue;

        // hide the "Occlusions..." option when we're not dealing with a Textline object
        boolean isTextline = attr.getAttrConfig().getAttrType().endsWith("textline");
        occlusions.setVisible(isTextline);
        occSeparator.setVisible(isTextline);

        Instant now = mediator.getCurrentFrame();
        if (now == null) {
          mediator.getDisplayWRTManager().setAttribute(null, null);
          wrt.setEnabled(false);
          wrt.setSelected(false);
        } else {
          boolean isDwrt = attr == mediator.getDisplayWRTManager().getAttribute();
          boolean dwrtable =
              (attr.getAttrValueAtInstant(now) instanceof HasCentroid
                  && attr.getDescriptor().getValidRange().contains(now));
          wrt.setEnabled(dwrtable);
          wrt.setSelected(isDwrt);
        }
      } else {
        attr = null;
        wrt.setEnabled(false);
        wrt.setSelected(false);
      }
      if (null != desc) {
        PropagateInterpolateModule proper = getMediator().getPropagator();
        p.setSelected(proper.isPropagatingThis(desc));
        v.setSelected(mediator.isThisValidNow(desc));
        resetMarks();
        super.show(invoker, x, y);
      }
    }