code: public void openPageCopyDialog(CmsSitemapTreeNode node, CmsSitemapTreeNodeData entry) {
  
          CmsObject cms = A_CmsUI.getCmsObject();
          try {
              CmsResource resource = cms.readResource(
                  entry.getClientEntry().getId(),
                  CmsResourceFilter.IGNORE_EXPIRATION);
              DialogContext context = new DialogContext(resource, node);
              CmsCopyPageDialog dialog = new CmsCopyPageDialog(context);
              String title = CmsVaadinUtils.getMessageText(Messages.GUI_COPYPAGE_DIALOG_TITLE_0);
              context.start(title, dialog);
          } catch (CmsException e) {
              LOG.error(e.getLocalizedMessage(), e);
              CmsErrorDialog.showErrorDialog(e);
          }
      }
docs: Opens the page copy dialog for a tree entry.<p>
  
  @param node the tree node widget
  @param entry the tree entry