//OpenMainSite in a new predefined window
function OpenMainSite()
{
  newwindow = window.open(
    "main.html",
    "VanStratenFotografie",
    "left="+(screen.width-1000)/2+",top="+(screen.height-700)/2+",width=1000,height=700,directories=no,location=no,menubar=no,resizable=no,toolbar=no scrollbars=no,statusbar=no");
    window.parent.opener=self;
    window.parent.close();
}