function change_height() {
    if(document.getElementById && !(document.all)) {
      height =
document.getElementById('myiframe').contentDocument.body.scrollHeight;
       document.getElementById('myiframe').style.height = height;
    }
    else if(document.all) {
        height = document.frames('myiframe').document.body.scrollHeight;
        document.all.myiframe.style.height = height;
    }
}