function displayLoginMessage(id) {
    var leftprop, topprop
    
    leftprop = getAbsoluteLeft(id);
    topprop = getAbsoluteTop(id);
    
    var loginbox = document.getElementById("loginPrompt");
    loginbox.style.display = "inline";
    loginbox.style.left = leftprop;
    loginbox.style.top = topprop;
}

function hideLoginMessage() {
    document.getElementById("loginPrompt").style.display = "none";
}

function getAbsoluteLeft(objectId) {
    o = document.getElementById(objectId)
    oLeft = o.offsetLeft
    while(o.offsetParent!=null) {
        oParent = o.offsetParent
        oLeft += oParent.offsetLeft
        o = oParent
    }
    return oLeft
}

function getAbsoluteTop(objectId) {
    o = document.getElementById(objectId)
    oTop = o.offsetTop
    while(o.offsetParent!=null) {
        oParent = o.offsetParent
        oTop += oParent.offsetTop
        o = oParent
    }
    return oTop
}