code: public static void showAbout() {
  
          final CmsPopup popup = new CmsPopup(Messages.get().key(Messages.GUI_ABOUT_DIALOG_TITLE_0));
          FlowPanel container = new FlowPanel();
          int height = 450;
          if (Window.getClientHeight() < height) {
              height = Math.max(300, Window.getClientHeight() - 50);
          }
          container.setHeight(height + "px");
          Frame frame = new Frame();
  
          frame.setWidth("100%");
          frame.setHeight("100%");
          frame.setUrl(CmsCoreProvider.get().getAboutLink());
          container.add(frame);
          popup.setMainContent(container);
          popup.center();
          popup.addDialogClose(null);
          CmsPushButton closeButton = new CmsPushButton();
          closeButton.setText(Messages.get().key(Messages.GUI_CLOSE_0));
          closeButton.setUseMinWidth(true);
  
          closeButton.setButtonStyle(ButtonStyle.TEXT, ButtonColor.BLUE);
          closeButton.addClickHandler(new ClickHandler() {
  
              /**
               * @see com.google.gwt.event.dom.client.ClickHandler#onClick(com.google.gwt.event.dom.client.ClickEvent)
               */
              public void onClick(ClickEvent event) {
  
                  popup.hide();
              }
          });
          popup.addButton(closeButton);
          popup.addDialogClose(null);
      }
docs: Shows the OpenCms about dialog.<p>