function openform() {
    document.getElementById('frameForm').style.display = 'inline';
    centering();
}

function closeform() {
    document.getElementById('frameForm').style.display = 'none';
}

function centering() {
    var div = document.getElementById('frameForm');
    var hscroll = document.documentElement.scrollLeft;
    var vscroll = document.documentElement.scrollTop;
    var top = Math.round(vscroll + ((document.documentElement.clientHeight / 2) - 245));
    var left = Math.round(hscroll + ((document.documentElement.clientWidth / 2) - 225));
    if (top < 0) top = 0;
    if (left < 0) left = 0;
    div.style.top = top + 'px';
    div.style.left = left + 'px';
}