After discussing the behavior in the support ticket I decided to post our findings here as well for anyone else that may have a similar problem.
This second issue is not the same as the original. This case is related to control selection on the design surface - it is possible to select a control from the ContentTemplate and then if you start typing from the keyboard VS will change the shown text, but the markup will not be updated.
This is not the correct way to modify the RadWindow's child controls - you must first select the Edit Templates
link from the end of the smart tag and then you can edit the control (e.g. via their Properties menu or smart tag). Once this is done you should select the End Template Editing
option from the smart tag of the RadWindow for the changes to take effect.
the Telerik team
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