This translucent (acrylic) effect is applicable for the Fluent theme only and can be applied to a Window, RadWindow or Popup.
The requirements for achieving the desired results are the following:
having the Fluent theme applied;
hosting the RadNavigationView in any of the above mentioned controls, for which this acrylic effect is applicable;
setting the PaneHeaderBackground and PaneBackground properties to Transparent.
I prepared a sample project for your convenience, which uses the RadWindow as a main window and has the Fluent theme applied using StyleManager.
Please, find the project attached to my reply, give it a try and let me know if you are happy with the result.
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