To reproduce: add a RadPageView in NavigationView and set the following property:


        Dim view As RadPageViewNavigationViewElement = TryCast(Me.RadPageView1.ViewElement, RadPageViewNavigationViewElement)

        view.CollapsedPaneWidth = 300 

The expected result is that the navigation view default's width is set to 300 when loading. However, it is adjusted when you expand and collapse the hamburger.