function Fensterweite()
{
 if (window.innerWidth) return window.innerWidth;
 else if (document.body && document.body.offsetWidth) return document.body.offsetWidth;
 else return 0;
}

function Fensterhoehe()
{
 if (window.innerHeight) return window.innerWidth;
 else if (document.body && document.body.offsetHeight) return document.body.offsetHeight;
 else return 0;
}


function GetAvailWidth(reserved) {

var x;

x=Fensterweite()-reserved;
if (x<0) return 0; else return(x);

}