var loaded = false;

function windowOverlayOnLoading() {
    loaded = true;
    document.getElementById('overlay').style.visibility = 'hidden';
    document.getElementById('messageBox').style.visibility = 'hidden';
}

function showOverlay(contents, showIfLoaded) {
    var x, y;
    if (self.innerHeight) // all except Explorer 
    { x = self.innerWidth; y = self.innerHeight; }
    else if (document.documentElement && document.documentElement.clientHeight) // Explorer 6 Strict Mode 
    { x = document.documentElement.clientWidth; y = document.documentElement.clientHeight; }
    else if (document.body) // other Explorers 
    { x = document.body.clientWidth; y = document.body.clientHeight; }

    document.getElementById('messageBox').style.left = (x - 300) / 2 + 'px'; // viewport minus width, divide by 2 
    document.getElementById('messageBox').style.top = (y - 100) / 2 + 'px'; // viewport minus height, divide by 2
    document.getElementById('overlay').style.visibility = 'visible';
    setTimeout('showMessageBox("' + contents + '", ' + showIfLoaded + ')', 1);
}

function showMessageBox(contents, showIfLoaded) {
    if (!loaded || showIfLoaded) {
        var msgDiv = document.getElementById('messageBox');
        if (msgDiv.childNodes[1].childNodes[0].childNodes.length == 0) { // if text node has been inserted, it will have a child node
            var msgP = document.createElement('p');
            msgP.className = 'MediumFont';
            var msgText = document.createTextNode(contents);
            msgP.appendChild(msgText);
            msgDiv.childNodes[1].insertBefore(msgP, msgDiv.childNodes[1].childNodes[0]);
        }
        else {
            msgDiv.childNodes[1].childNodes[0].childNodes[0].nodeValue = contents;
        }

        msgDiv.style.visibility = 'visible';
    }
}