If you load an entire page in the RadWindow there will be no way to have the tooltips ignore the iframe bounds (the page is actually loaded in an iframe).
What you can consider, however, is the ContentTemplate the control offers, as it will still be a part of the main page and the tooltips will not be bound in the window: http://demos.telerik.com/aspnet-ajax/window/examples/contenttemplatevsnavigateurl/defaultcs.aspx
. This demo shows and explains the differences, pros and cons for both modes.
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