code: private boolean commentLinesBefore( String content, int line ) {
          int offset = rootElement.getElement(line).getStartOffset();
          // Start of comment not found, nothing to do
          int startDelimiter = lastIndexOf(content, getStartDelimiter(), offset - 2);
          if (startDelimiter < 0)
              return false;
          // Matching start/end of comment found, nothing to do
          int endDelimiter = indexOf(content, getEndDelimiter(), startDelimiter);
          if (endDelimiter < offset & endDelimiter != -1)
              return false;
          // End of comment not found, highlight the lines
          doc.setCharacterAttributes(startDelimiter, offset - startDelimiter + 1, comment, false);
          return true;
      }
docs: /*
  Highlight lines when a multi line comment is still 'open'
  (ie. matching end delimiter has not yet been encountered)