code: function ()
  	{
  		var aoOpen = this.s.dt.aoOpenRows;
  		var iVisible = this.s.dt.oApi._fnVisbleColumns( this.s.dt );
  
  		for ( var i=0, iLen=aoOpen.length ; i<iLen ; i++ ) {
  			aoOpen[i].nTr.getElementsByTagName('td')[0].colSpan = iVisible;
  		}
  	}
docs: Alter the colspan on any fnOpen rows