function externalLinks() {
	if (!document.getElementsByTagName) {
		return;
	}
	var anchors = document.getElementsByTagName('a');
	for (var i=0; i<anchors.length; i++) {
		var anchor = anchors[i];
		if (anchor.getAttribute('href') && anchor.getAttribute('rel') == 'external') {
			anchor.target = '_blank';
		}
	}
}
addListener(window, 'load', externalLinks);