/**
 * Displays a new window centered on the screen.
 *
 * @param url The page to display.
 * @param name Name of the window.
 * @param w Width of the new window.
 * @param h Height of the new window.
 */
function popupWindow(url, name, w, h)
{
   x = screen.availWidth/2-w/2;
   y = screen.availHeight/2-h/2;
   var CbFilm = window.open(url, name, 'width='+w+', height='+h+', left='+x+', top='+y+', screenX='+x+', screenY='+y+', resizable=yes, scrollbars=yes');
   CbFilm.focus();

   if (CbFilm) return false;
   else return true;
}