Within my master page I have a RadSplitter layout. One of the Splitter panes contains the MasterPage contentholder and since the requirement called for only this area to update on the click of a navigation node item I placed an iframe within the contentholder (All content in iframe is located within the site itself). I was wondering however, if there is a way to utilize and show the RadAjaxLoadingPanel after the navigation node item has been clicked and hides when the page in the iframe is finished loading?

Hi Matthew,

Since the iframe is redirecting to a new page, the initiated load of the form is not a postback, but rather an entirely new page load. Therefore, RadAjaxLoadingPanel simply does not have a created control to be applied on, thus, this scenario is not supported.

One possible approach to achieve the desired functionality is to use a RadWindow with ShowContentDuringLoad set to false as demonstrated in the following demo:
 Window / Show Content During Load
Please note that you could remove the extra styling of RadWindow and display it as a regular iframe.

An alternative approach would be to try showing the loading panel explicitly. You could initiate the loading over a given panel on user node click and then end it when the iframe completely loads its page using the onload event of the iframe:

I believe this will prove helpful. 

Kind regards,
Eyup
the Telerik team