Are you using Test Studio Standalone version or the Visual Studio Plug-in version? In the standalone version we recently added a new "OnBeforeUnload" dialog handler which is meant to handle this very dialog. (it's missing in the Visual Studio Plug-in version for which we have a bug filed).
Another way to handle this dialog is to use our UnexpectedDialogAction feature, which allows the test to automatically handle unexpected dialogs. You can reed more about it here.
There are other ways around this, by using a blind mouse click or a blind Enter key press as seen here
. Also check out and this video here
Let me know if you have any further questions!
the Telerik team
Check out the Test Studio roadmap
to find out more about the new performance testing functionality coming in our R2 2011 release this September!
Have you looked at the new Online User Guide
for Telerik Test Studio?