var win; 
function popme(filename) {
	if (win && !win.closed) {
		win.close();
	}
	win = window.open(filename,"","scrollbars,width=700,height=600,left="+(screen.width - 400) / 2+",top="+(screen.height - 400) / 2);
	if (!win.opener) {
		win.opener = window;
	}
}