function setExternalLinks() {
	if ( !document.getElementsByTagName ) {
		return null;
	}
	var anchors = document.getElementsByTagName( "a" );
	for ( var i = 0; i < anchors.length; i++ ) {
		var anchor = anchors[i];
		if ( anchor.getAttribute( "href" ) && anchor.className == "ext" ) {
			anchor.setAttribute( "target", "_blank" );
		}
	}
}

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

addLoadEvent(setExternalLinks);