code: public String getHighlightMode() {
  
          // read edited resource
          CmsResource resource = null;
          try {
              resource = getCms().readResource(getParamResource());
          } catch (CmsException e) {
              // ignore
          }
  
          if (resource != null) {
              // determine resource type
              int type = resource.getTypeId();
              if (CmsResourceTypeJsp.isJspTypeId(type)) {
                  // JSP file
                  return HIGHLIGHT_TYPE_JSP;
              }
              if (CmsResourceTypeXmlContent.isXmlContent(resource) || CmsResourceTypeXmlPage.isXmlPage(resource)) {
                  // XML content file or XML page file
                  return HIGHLIGHT_TYPE_XML;
              }
              // all other files will be matched according to their suffix
              int dotIndex = getParamResource().lastIndexOf('.');
              if (dotIndex != -1) {
                  String suffix = getParamResource().substring(dotIndex + 1);
                  if (CmsStringUtil.isNotEmpty(suffix)) {
                      // there is a suffix, determine matching syntax highlighting
                      int typeIndex = HIGHLIGHT_TYPES_LIST.indexOf(suffix.toLowerCase());
                      if (typeIndex != -1) {
                          return HIGHLIGHT_TYPES_LIST.get(typeIndex);
                      }
                  }
              }
          }
          // return HTML type as default
          return HIGHLIGHT_TYPE_HTML;
      }
docs: Returns the syntax highlighting type for the currently edited resource.<p>
  
  @return the syntax highlighting type