code: private void showProgress() {
  
          removeContent();
          displayDialogInfo(
              org.opencms.gwt.client.Messages.get().key(org.opencms.gwt.client.Messages.GUI_UPLOAD_INFO_UPLOADING_0),
              false);
          m_selectionSummary.removeFromParent();
          List<String> files = new ArrayList<String>(getFilesToUpload().keySet());
          Collections.sort(files, String.CASE_INSENSITIVE_ORDER);
          m_progressInfo = new CmsUploadProgressInfo(files);
          m_progressInfo.setContentLength(m_contentLength);
          m_contentWrapper.add(m_progressInfo);
          m_updateProgressTimer.scheduleRepeating(UPDATE_PROGRESS_INTERVALL);
          startLoadingAnimation(Messages.get().key(Messages.GUI_UPLOAD_CLIENT_LOADING_0), 0);
          setHeight();
          changeHeight();
      }
docs: Starts the upload progress bar.<p>