Focus Border Behavior Differs Between Windows App SDK 1.5 and 1.6

Describe the bug

The behavior of focus borders has changed between Windows App SDK versions 1.5 and 1.6.
In Windows App SDK 1.5, when a control (e.g., a button) placed inside a ScrollViewer gains focus via the keyboard, clicking outside the control dismisses the focus border, indicating that the control has lost focus.
In Windows App SDK 1.6, the same action does not dismiss the focus border. Even after clicking outside the control, the focus border remains visible, indicating that the control retains focus.
This behavior change affects how focus is visually managed and may lead to inconsistencies in user experience, especially in scenarios relying on traditional focus dismissal behavior.

Steps to reproduce the bug

1. Create a WinUI 3 application.
2. Ensure that the installed Windows App SDK version is 1.6. If not, update to 1.6.
3. In MainWindow.xaml file, replace the existing code with following code .

    <ScrollViewer>
        <StackPanel Orientation="Vertical" HorizontalAlignment="Center" VerticalAlignment="Center" Spacing="20">
            <CheckBox Content="Two-state CheckBox"/>
            <Button x:Name="myButton" Click="myButton_Click">Click Me</Button>
        </StackPanel>
    </ScrollViewer>

4. Build and run the application.
5. Use the keyboard to focus on the control(e.g., a button) .
6. Click outside the control using the mouse.

Sample projects with Windows App SDK 1.5 and 1.6 attached to reproduce the issue.
Apps.zip

Expected behavior

The focus border around the control should be dismissed, indicating the loss of focus (as in Windows App SDK 1.5).

Actual Behavior

The focus border remains visible around the control, even after clicking outside (as in Windows App SDK 1.6).

Screenshots

No response

NuGet package version

Windows App SDK 1.6.3: 1.6.241114003

Packaging type

Packaged (MSIX), Unpackaged

Windows version

Windows 10 version 22H2 (19045, 2022 Update)

IDE

Visual Studio 2022

Additional context

If this is intentional, guidance on managing focus dismissal would be appreciated.

Start with the attached Apps.zip and reproduce the behavior using the MainWindow.xaml markup in the issue under Windows App SDK 1.5 and 1.6. Compare keyboard focus followed by an outside mouse click, and consider the issue done when the 1.6 behavior is explained or corrected to match the stated expected focus-border dismissal.