Display loading when iframe is loading

---

Here's a quick solution for most of the cases:

CSS:

.iframe-loading { 
    background:url(/img/loading.gif) top no-repeat; 
}

HTML:

<div class="iframe-loading">
    <iframe src="http://your_iframe_url_goes_here"  onload="$('.iframe-loading').css('background-image', 'none');"></iframe>
</div>