function addLoadEvent(func) {
	var oldonload = window.onload;
	if (typeof window.onload != 'function') {
		window.onload = func;
	} else {
		window.onload = function() {
			if (oldonload) {
				oldonload();
			}
			func();
		}
	}
}

function externalLinks() {

	var externalclass = "external";

	if (!document.getElementsByTagName) return false;
	if (!document.getElementsByTagName("a")) return false;
	var lnks = document.getElementsByTagName ("a");
	for (var i=0; i<lnks.length; i++) {
		if (lnks[i].className == externalclass) {
			lnks[i].target = "_blank";
		}
	}
}

addLoadEvent(externalLinks);