try {
  document.execCommand("BackgroundImageCache", false, true);
} catch(err) {}
function showResolution() {
	document.write('Your screen resolution is ' + screen.width + 'x' + screen.height);
}
function toggleCheckbox(id)
{
	var elem = document.getElementById(id);
	elem.checked = !elem.checked;
}
function changeClass(elem,cls)
{
	if(elem.className)
		elem.className=cls;
}
function GetXmlHttpObject()
{
	var xmlHttp = null;
	try
	{
		// Firefox, Opera 8.0+, Safari
		xmlHttp = new XMLHttpRequest();
	}
	catch (e)
	{
		// Internet Explorer
		try
		{
			xmlHttp = new ActiveXObject("Msxml2.XMLHTTP");
		}
		catch (e)
		{
			xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
		}
	}
	return xmlHttp;
}