function popup(url, popWidth, popHeight) {
	var winleft = (screen.width - popWidth) / 2;
	var wintop = (screen.height - popHeight) / 2;
	popwin=window.open(url, "Picture", "left="+winleft+", top="+wintop+", width="+popWidth+", height="+popHeight+" ,scrollbars=yes, resizable=yes");
	if (parseInt(navigator.appVersion) >= 4) { 
		popwin.window.focus();
	} 
}