var _POPUP_FEATURES = 'location=1,statusbar=1,menubar=1';

function isUndefined(v) {
	var undef;
	return v===undef;
}

function raw_popup(url, target, features) {
	// pops up a window containing url optionally named target, optionally having features
	if (isUndefined(features)) features = _POPUP_FEATURES;
	if (isUndefined(target)) target   = '_blank';
	var theWindow = window.open(url, target, features);
	theWindow.focus();
	return theWindow;
}

function link_popup(src, features) {
	// to be used in an html event handler as in: <a href="..." onclick="link_popup(this,...)" ...
	// pops up a window grabbing the url from the event source's href
	return raw_popup(src.getAttribute('href'), src.getAttribute('target') || '_blank', features);
}