accessibility: Ctrl+Home then Down arrow key go to system bar for WebView2 app

[danny8002]

Describe the bug

Seems WinUI2 is not well-integrated with WebView2 for accessibility issue in scan mode. Ctrl+Home will move focus to the top of the webpage content, but subsequent down arrow presses will navigate to the app system bar.

try Win32 + WebView2, this issue don't repro. so this should be WinUI2 bug.

Steps to reproduce the bug

1. Launch the sample app https://github.com/MicrosoftEdge/WebView2Samples/tree/main/GettingStartedGuides/WinUI2_GettingStarted/MyUWPGetStartApp

2. (optional) Update WinUI2 2.8.6, WebView2 1.0.2903.40

3. Turn On Narrator, "Tap" to one of page elements

4. "Caps Lock" + "Space" to turn on scan mode

5. Press Ctrl + Home to move to the top of the content.

6. Use the down arrow key to start navigating the content.
   => hear "MyUWPGetStartApp" from system bar
   expect => the next element of the page content

Expected behavior

Actual:
After pressing Ctrl+Home, the screen reader first moves focus to the top of the webpage content, but subsequent down arrow presses navigate to system bar like the title bar, minimize button, maximalize button

Expected:
Focus should remain within the content after using Ctrl+Home, and down arrow navigation should continue consistently from the top of the webpage content without jumping through other elements like the system title bar.

Screenshots

No response

NuGet package version

WinUI 2 - Microsoft.UI.Xaml 2.8.2

Windows version

Windows 11 (24H2): Build 26100

Additional context

No response