code: public void loadAndShow() {
  
          // enable or disable the OK button
          if (getFilesToUpload().isEmpty()) {
              disableOKButton(Messages.get().key(Messages.GUI_UPLOAD_NOTIFICATION_NO_FILES_0));
              setDragAndDropMessage();
          } else {
              enableOKButton();
              removeDragAndDropMessage();
          }
          m_uploadedFiles = null;
          // set the user info
          displayDialogInfo(Messages.get().key(Messages.GUI_UPLOAD_INFO_SELECTION_0), false);
          // set the selection summary
          updateSummary();
  
          // add a upload button
          m_uploadButton.createFileInput();
  
          // show the popup
          if (!isShowing()) {
              Scheduler.get().scheduleDeferred(new ScheduledCommand() {
  
                  /**
                   * @see com.google.gwt.core.client.Scheduler.ScheduledCommand#execute()
                   */
                  public void execute() {
  
                      setContentWrapperHeight();
                      center();
                  }
              });
          }
          center();
      }
docs: Loads and shows this dialog.<p>