function html_popupCenterWindow(url, wname, w, h, f) {
	var gab = 20;
	var wx = (window.screen.width-w)/2;
	var wy = (window.screen.height-h)/2;
	if(wy > gab) {
	wy -= gab;
	}
	var features = "width="+w+",height="+h+",left="+wx+",top="+wy;
	if (f != null)
		features += "," + f;
	var p=window.open(url, wname, features);
	p.focus();
	return p;
}
function popTvcf()
{
	html_popupCenterWindow('popup_tvcf.html', 'tvcf', 450, 450, null);
}