It is possible that the AJAX request scrolls the page. This is a default browser behavior when dealing with postbacks and AJAX requests and there are numerous resources on the net related to handling this page scrolling. The behavior should manifest after any request from this module, not only when a RadWindow is being shown.
If I have misunderstood you and the actual page does not scroll I am not certain what the exact problem may be without being able to reproduce it, yet I can suggest that you inject the call to the RadAlert as explained in this help artiicle
. You may add a small timeout when calling the RadAlert (even 0ms may suffice). It if does not help you can store a reference to the alert popup (the radalert() method returns it) and call its center() method after it is shown (you can again try adding a timeout if it does not work initially).
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