code: protected void addCancelButton() {
  
          if (m_editorDialog != null) {
              m_cancelButton = new CmsPushButton();
              m_cancelButton.setText(Messages.get().key(Messages.GUI_BUTTON_CANCEL_TEXT_0));
              m_cancelButton.setUseMinWidth(true);
              m_cancelButton.setButtonStyle(ButtonStyle.TEXT, ButtonColor.BLUE);
              m_cancelButton.addClickHandler(new ClickHandler() {
  
                  public void onClick(ClickEvent event) {
  
                      cancelEdit();
                  }
              });
              m_editorDialog.addButton(m_cancelButton);
          }
      }
docs: Adds a cancel button to the dialog.<p>