/* Create XMLHttpRequest */
function createXMLHttpRequest() {
	var xmlHttp;
	
	try {
		xmlHttp = new XMLHttpRequest();	// Firefox, Opera 8.0+, Safari
	} catch (e) {
		// Internet Explorer
		try {
			xmlHttp = new ActiveXObject("Msxml2.XMLHTTP");
	    } catch (e) {
			try {
				xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
			} catch (e) {
				alert("Your browser does not support AJAX!");
			}
	    }
	}
	
	return xmlHttp;
}

/* Cross Browser Event Handler */
function addEvent(obj, evType, fn){
	if (obj.addEventListener){
		obj.addEventListener(evType, fn, true);
		return true;
	} else if (obj.attachEvent){
		var r = obj.attachEvent("on" + evType, fn);
		return r;
	} else {
		return false;
	}
}

/* Toggle display of a div between block and none */
function toggle_div(id) {
	var div, div_style;
	div = document.getElementById(id);
	div_style = div.style;
	div_style.display = (div_style.display==''||div_style.display=='block')?'none':'block';
}

/* Set the display style of an element (usually a div) */
function set_div(id, value) {
	var div, div_style;
	div = document.getElementById(id);
	div_style = div.style;
	div_style.display = value;
}

/* Delete all children of a node */
function remove_children(el) {
	while(el.firstChild) {
		el.removeChild(el.firstChild);
	}
}

xmlHttp = createXMLHttpRequest();