function oeffneFenster ( myURL, myName, myWidth, myHeight )
    {
      myCenterX = ( screen.width  / 2 ) - ( myWidth / 2 ) ;
      myX       = ( "screenX=" + myCenterX );
      myCenterY = ( screen.height / 2 ) - ( myHeight / 2 );
      myY       = ( "screenY=" + myCenterY );
      myWidth  = ( "width=" + myWidth );
      myHeight = ( "height=" + myHeight );
      myOptions = ( myWidth + "," + myHeight + "," + myX + "," + myY + "," + 'status=no, toolbar=no, menubar=no, location=no, resizable=no, titlebar=no, scrollbars=no, fullscreen=no' );
      Fenster = window.open( myURL, myName, myOptions );
      if (navigator.appName != "Netscape")
      { Fenster.moveTo (myCenterX,myCenterY); }
}