To use kango.* APIs you must include script kango_api.js in your popup html and use it only after onReady event:
<script type="text/javascript" src="kango-ui/kango_api.js"></script>
popup.html:
<html>
<head>
<script type="text/javascript" src="kango-ui/kango_api.js"></script>
<script type="text/javascript" src="jquery.min.js"></script>
<script type="text/javascript" src="popup.js"></script>
</head>
<body>
<textarea id="popup-properies" rows="4" cols="60"></textarea><br/>
<button id="popup-close" type="button">Close popup</button>
<button id="popup-resize" type="button">Resize popup</button>
</body>
</html>
popup.js:
KangoAPI.onReady(function() {
$('#popup-close').click(function(event) {
KangoAPI.closeWindow()
});
$('#popup-resize').click(function(event) {
KangoAPI.resizeWindow(600, 600);
$('#popup-properies').attr('rows', 8);
});
alert(kango.browser.getName());
});