Display Loading Panel on Popup Loading

/* Code to Display Loading Panel for Popup Window */

crmForm.all.tab1Tab.onclick = function () {
    var iframe = document.getElementById("IFRAME_QueryXML");
    iframe.style.display = 'none';

    var AddedDiv = document.getElementById("MyDiv");
    if (AddedDiv == null) {
        var NewDiv = document.createElement("div");
        NewDiv.id = "MyDiv";
        NewDiv.style.position = "relative";
        NewDiv.style.left = "50%";
        NewDiv.style.top = "50%";
        var img = document.createElement("IMG");
        img.src = "/../ISV/Survey/Images/Progress.gif";
        NewDiv.appendChild(img);
        iframe.parentNode.appendChild(NewDiv);
    }
    crmForm.all.IFRAME_QueryXML.src = crmForm.all.IFRAME_QueryXML.src;
    iframe.onreadystatechange = function () {
        if (iframe.readyState == "complete") {
            document.getElementById("MyDiv").style.display = 'none';
            document.getElementById("IFRAME_QueryXML").style.display = 'inline';

        }
    }
}