code: private boolean performChangeOperation(boolean recursive) throws CmsException {
  
          // on recursive property changes display "please wait" screen
          if (recursive && !DIALOG_WAIT.equals(getParamAction())) {
              // return false, this will trigger the "please wait" screen
              return false;
          }
  
          // lock the selected resource
          checkLock(getParamResource());
          // change the property values
          List changedResources = null;
          if (CmsStringUtil.isNotEmptyOrWhitespaceOnly(getParamOldValue())) {
              changedResources = getCms().changeResourcesInFolderWithProperty(
                  getParamResource(),
                  getParamPropertyName(),
                  getParamOldValue(),
                  getParamNewValue(),
                  recursive);
          } else {
              changedResources = setPropertyInFolder(
                  getParamResource(),
                  getParamPropertyName(),
                  getParamNewValue(),
                  recursive);
          }
          setChangedResources(changedResources);
          return true;
      }
docs: Performs the main property change value operation on the resource property.<p>
  
  @param recursive true, if the property value has to be changed recursively, otherwise false
  @return true, if the property values are changed successfully, otherwise false
  @throws CmsException if changing is not successful