var IE = document.all?true:false;

function setFrameHeight() {
	document.getElementById("mainframe").height = Math.max(400,iframeContent("mainframe").body.offsetHeight);
}
function iframeContent(myFrameName) {
	var x = document.getElementById(myFrameName);
	if (IE) {return x.contentWindow.document}
	else {return x.contentDocument}
}