function openWindow(url, x, y)
{
    var salt = Math.round(Math.random() * 100000) + x + y;
    var window_left = (screen.width-x)/2;
    var window_top = (screen.height-y)/2;
    w=window.open('showimage.php?' + url + '&' + x + '&' + y,
					'mywindow' + salt,
					'width=' + x + ',height=' + y +
						',top=' + window_top + ',left=' + window_left + ',resizable=no,scrollbars=yes');
    w.focus();
}