public void dispose() {
   ISiteModel model = (ISiteModel) getPage().getModel();
   if (model != null) model.removeModelChangedListener(this);
   super.dispose();
 }
  public void createClient(Section section, FormToolkit toolkit) {

    section.setLayout(FormLayoutFactory.createClearGridLayout(false, 1));
    Composite container = toolkit.createComposite(section);
    container.setLayout(FormLayoutFactory.createSectionClientGridLayout(false, 2));
    container.setLayoutData(new GridData(GridData.FILL_HORIZONTAL));

    GridData data = new GridData(GridData.FILL_BOTH);
    section.setLayoutData(data);

    fNameText = new FormEntry(container, toolkit, MDEUIMessages.CategoryDetails_name, null, false);
    fNameText.setFormEntryListener(
        new FormEntryAdapter(this) {
          public void textValueChanged(FormEntry text) {
            try {
              if (text.getValue().length() <= 0 || alreadyExists(text.getValue())) {
                setValue(PROPERTY_NAME);
                String message = MDEUIMessages.CategoryDetails_alreadyExists;
                MessageDialog.openError(
                    MDEPlugin.getActiveWorkbenchShell(),
                    MDEUIMessages.CategoryDetails_alreadyExists_title,
                    message);
              } else {
                applyValue(PROPERTY_NAME, text.getValue());
              }
            } catch (CoreException e) {
              MDEPlugin.logException(e);
            }
          }
        });
    limitTextWidth(fNameText);
    fNameText.setEditable(isEditable());

    fLabelText =
        new FormEntry(container, toolkit, MDEUIMessages.CategoryDetails_label, null, false);
    fLabelText.setFormEntryListener(
        new FormEntryAdapter(this) {
          public void textValueChanged(FormEntry text) {
            try {
              applyValue(PROPERTY_TYPE, text.getValue());
            } catch (CoreException e) {
              MDEPlugin.logException(e);
            }
          }
        });
    limitTextWidth(fLabelText);
    fLabelText.setEditable(isEditable());

    fDescriptionText =
        new FormEntry(container, toolkit, MDEUIMessages.CategoryDetails_desc, SWT.WRAP | SWT.MULTI);
    fDescriptionText.getText().setLayoutData(new GridData(GridData.FILL_BOTH));

    fDescriptionText.getLabel().setLayoutData(new GridData(GridData.VERTICAL_ALIGN_BEGINNING));

    fDescriptionText.setFormEntryListener(
        new FormEntryAdapter(this) {
          public void textValueChanged(FormEntry text) {
            try {
              applyValue(PROPERTY_DESC, text.getValue());
            } catch (CoreException e) {
              MDEPlugin.logException(e);
            }
          }
        });
    limitTextWidth(fDescriptionText);
    fDescriptionText.setEditable(isEditable());
    toolkit.paintBordersFor(container);
    section.setClient(container);

    ISiteModel model = (ISiteModel) getPage().getModel();
    if (model != null) model.addModelChangedListener(this);
  }