// custom size, centered popup
function custom_sized_centered_popup(width, height)
{
mypopup = window.open("http://indoserver.web.id/livechat.html","PopupWindow","menubar=0,toolbar=0,resizable=1,width=" + width + ",height=" + height);

// calculate the center of the page
x = (screen.availWidth - width) / 2;
y = ((screen.availHeight - height) / 2);

// move to the center of the page
mypopup.moveTo(x, y);
}