this is not standard PHP functionality, and neither is it particularly new and/or weird. take this javascript example, for example:
<script type="text/javascript">
function popUp(url, window_name, window_width, window_height, scroll, resize)
{ settings=
"toolbar=no,location=no,directories=no,"+
"status=no,menubar=no,scrollbars="+scroll+","+
"resizable="+resize+",width="+window_width+",height="+window_height;
NewWindow=window.open(url,window_name,settings);
}
</script>
<a href="javascript:popUp('/some/url/blah.html', 'blah', 200, 300, 'no', 'yes');">Blah</a>