Using the RadAjaxLoadingPanel is not possible during a redirect. Actually - any AJAX-enabled control will not fit your scenario, as they are loaded quite late in the page lifecycle - after the window.onload event fires and are available, at earliest, in the Sys.Application.Load
event, at which point your entire page has loaded.
What you can do is create two divs in your page - one initially shown with a loading message and one that has the main content, initially hidden (via CSS, of course) and you can change their display in the Sys.Application.Load event. A small example is attached to this thread. Please note the utilization of the setTimeout method to delay the switch of the panels in order for the effect to be more visible and to simulate a heavy page being loaded.
Please note that having controls in initially hidden containers may sometimes result in unexpected layout changes, so you may leave the main contents visible, just hide the loading sign (which will need a high z-index, of course). You may additionally style the loadingSign div to match your needs.
the Telerik team
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