Answer by Joe White for WPF and initial focus

I found another possible solution. Mark Smith posted a FirstFocusedElement markup extension for use with FocusManager.FocusedElement.

<UserControl x:Class="FocusTest.Page2"    xmlns:FocusTest="clr-namespace:FocusTest"    FocusManager.FocusedElement="{FocusTest:FirstFocusedElement}">