code: void submit() {
  
          String siteRoot = (String)m_siteComboBox.getValue();
          if (!m_context.getCms().getRequestContext().getSiteRoot().equals(siteRoot)) {
              A_CmsUI.get().changeSite(siteRoot);
              if (CmsStringUtil.isEmptyOrWhitespaceOnly(siteRoot) || OpenCms.getSiteManager().isSharedFolder(siteRoot)) {
                  // switch to explorer view when selecting shared or root site
  
                  Page.getCurrent().open(CmsCoreService.getFileExplorerLink(A_CmsUI.getCmsObject(), siteRoot), "_top");
                  return;
              }
          } else {
              siteRoot = null;
          }
          m_context.finish(null, siteRoot);
      }
docs: Submits the dialog action.<p>