var bShowPopup = false;
function showPopup(evt) {
    var oEvent = (evt) ? evt : window.event;

    var oPopup = document.getElementById('popup');
    if (oPopup.style.display == 'none') {
        oPopup.style.top = (pointerY(oEvent) - 200) + 'px';
        oPopup.style.left = (pointerX(oEvent) - 200) + 'px';
        oPopup.style.display = '';    
    }
}

function hidePopup(evt) {
    var oPopup = document.getElementById('popup');
    if (oPopup.style.display != 'none') {
        oPopup.style.display = 'none';    
    }
}

function pointerX(event) {
    return event.pageX || (event.clientX +
      (document.documentElement.scrollLeft || document.body.scrollLeft));
}

function pointerY(event) {
    return event.pageY || (event.clientY +
        (document.documentElement.scrollTop || document.body.scrollTop));
}