I would like the ability to add attributes to the 'RadPane' iframe server side, example problem:

Suppose you have a page with an embedded you-tube video, the full screen option will be disabled as the iframe attribute 'allowfullscreen' is missing, this can be worked around using the following technique: 

http://www.telerik.com/forums/youtube-full-screen

However if the initial page has the youtube video the page needs to be loaded twice as chrome only picks it up on the second page load (as its been set in javascript).

If this is not possible, I would recommend you copy the approach used on radwindow (http://www.telerik.com/forums/youtube-video-in-popup-window-full-screen) e.g. 

    function setIframeAttr(sender, args) {
        var frame = sender.get_contentFrame();
        if (frame) {
            frame.setAttribute("allowfullscreen", "true");
        }
    }

With a client side event "OnClientBeforeShow" (OnClientShow does not work in internet explorer).

This isn't a priority but since there is a hack involved with reloading the page it may be worthwhile making it easier.

Chris