function is() {
  var agent = navigator.userAgent.toLowerCase();
  this.major = parseInt(navigator.appVersion);
  this.minor = parseFloat(navigator.appVersion);
  this.ns = ((agent.indexOf('mozilla') != -1) &&
            (agent.indexOf('spoofer') == -1) &&
            (agent.indexOf('compatible') == -1) &&
            (agent.indexOf('opera') == -1) &&
            (agent.indexOf('webtv') == -1));

 var weite = screen.width;
 
 if(weite>805)
 {
  if(this.ns)
  {
  neuegroessens();
  }
  else
  {
  neuegroesse();
  }
 }
}

function neuegroessens()
{
window.outerHeight=600;
window.outerWidth=770;
}

function neuegroesse()
{
window.resizeTo(780,600);
}