code: function( element, index ) {
  			if ( typeof index == 'undefined' ) {
  				index = this._.focusList.length;
  				this._.focusList.push( new Focusable( this, element, index ) );
  			} else {
  				this._.focusList.splice( index, 0, new Focusable( this, element, index ) );
  				for ( var i = index + 1; i < this._.focusList.length; i++ )
  					this._.focusList[ i ].focusIndex++;
  			}
  		}
docs: Adds element to dialog's focusable list.
  
  @param {CKEDITOR.dom.element} element
  @param {Number} [index]