code: private void enableSetButton(boolean enabled) {
  
          if (enabled) {
              if (m_addPermissionSetButton == null) {
                  m_addPermissionSetButton = new Button(FontAwesome.PLUS);
                  m_addPermissionSetButton.addStyleName(OpenCmsTheme.BUTTON_ICON);
                  m_addPermissionSetButton.addClickListener(new ClickListener() {
  
                      private static final long serialVersionUID = 1L;
  
                      public void buttonClick(ClickEvent event) {
  
                          onSelect();
                      }
                  });
                  m_main.addComponent(m_addPermissionSetButton);
              }
          } else if (m_addPermissionSetButton != null) {
              m_main.removeComponent(m_addPermissionSetButton);
              m_addPermissionSetButton = null;
          }
      }
docs: Sets the add permission button enabled.<p>
  
  @param enabled <code>true</code> to enable the button