In Internet Explorer, windows opened using window.open from another window, exist in the same thread as the parent window.This is not true for Mozilla and Safari because there all child windows are opened in different threads. Thus when you initiate an AJAX request inthe child window and close this window, it will be aborted in Mozilla, because closing the window destroys the thread which is running the AJAX request.This worked in IE because the child window runs in the same thread as the parent and it does not destroy the AJAX request when it closes.
To resolve this issue you need to create AJAX requests in the context of the parent window and apply a slight timeout on it as shown in Example 1 .
You should use a similar technique when using the Telerik RadWindow control. You still need to force the execution in the parentWindow, otherwise, the request will be cancelled, once the window is closed. You can see this technique in Example 2 .
Note that Example 2 uses setTimeout to force execution in the parentWindow's context since it will not get closed. Another thing to keep in mind is that one should not reference the child window in your setTimeout-invoked code as it might have already been destroyed.