[artcraft]

var str:String = 'abcd'+newline+'efgh'+newline+'ijkl';

function isFirst (str:String, pos:Number):Boolean {	
	if (pos-1 == str.indexOf(String.fromCharCode(13), pos-1)) {
		return (true);
	}else{
		return (false);
	}
}

trace(isFirst(str, 5)); // true  ( e )
trace(isFirst(str, 6)); // false  ( f )