code: function createCaretContainer(fill) {
            var caretContainer = dom.create('span', { id: caretContainerId, 'data-mce-bogus': true, style: debug ? 'color:red' : '' });
  
            if (fill) {
              caretContainer.appendChild(ed.getDoc().createTextNode(INVISIBLE_CHAR));
            }
  
            return caretContainer;
          }
docs: Creates a caret container bogus element