/// <reference name="MicrosoftAjax.js"/>
function ToggleVisibility(elementID, sourceNodeName, event) {
    var eventObject = event || window.event;
    var source = eventObject.srcElement || eventObject.target;
    if (source.nodeName != sourceNodeName)
        return;

    var element = document.getElementById(elementID);
    if (!element)
        return false;
    element.style.display = element.style.display == "none" ? "block" : "none";
}