function window_height() {
                  var way = window.frames[0];
                    //Firefox etc
                    document.getElementById("main_frame").setAttribute("height",'0px') ;
                    if (way.innerHeight) {
                        return way.innerHeight;
                    } else if (way.document.body && way.document.body.offsetHeight) {
                        return way.document.body.offsetHeight;
                    }
                   //IE 6 strict Mode
                    var win = document.getElementById("main_frame").contentWindow;
                    if (   win.document.documentElement && win.document.documentElement.clientHeight)   {
                        return win.document.documentElement.scrollHeight;
                    }
                    // andere IE
                    else if (   win.document.body)
                    {
                        return  win.document.body.scrollHeight;
                    }
              }

            function setIframeHeight(s) {
                    var h = window_height()+40+s;
                    document.getElementById("main_frame").setAttribute("height",h+'px') ;
            }