var MAX_LINES = 12;
var begin = '<ul><li>';
var middle = '</li><li>';
var end = '</li></ul>';

function trace(msg) {
	var output_window = document.getElementById("trace");
	var lines = output_window.innerHTML.toLowerCase();
	var lineList;
	
	if (lines.length > 0) {
		lineList = lines.substring(begin.length, lines.length - end.length).split(middle);
		while (lineList.length >= MAX_LINES) { lineList.shift(); }
		lineList.push(msg);
	}
	else {
		lineList = [ msg ];
	}
	
	output_window.innerHTML = begin +lineList.join(middle) +end;
}