You can set VisibleOnPageLoad Property of RadNotification to false and show RadNotification whenever you want as follows.
<telerik:RadNotificationID="RadNotification1"runat="server"VisibleOnPageLoad="false"Title="Sample Title"Text="Simple text content"ShowCloseButton="true">
Hope this helps.
answered on 30 Oct 2012, 09:06 AM
I have just answered your support ticket on the matter and for your convenience and for others that may have a similiar question I am pasting my reply here:
The RadNotification control supports two main ways of getting updated content - a client callback and a webservice. Client callbacks are lighter than postbacks because they do not go through the rendering stages of the page, yet they will still hit the page load event. Webservices, on the other hand, are not related to a given page and thus they will not affect it. You can see this in the following demos:
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