ContentDialog focus highlight is shown when dialog is opened via a keyboard event

[daverayment]

Describe the bug

When a ContentDialog is shown which contains interactive controls, the display of the focus highlight is inconsistent:

1. If the dialog is opened via a button click, the highlight is not shown. The first interactive control on the dialog is focussed, but the highlight is not shown.
2. If the dialog is opened via a KeyUp event handler or in response to a KeyboardAccelerator invocation, the focus highlight is shown.

Steps to reproduce the bug

1. Create a new project in Visual Studio. Choose "Blank App, Packaged (WinUI 3 in Desktop)" as the project template.

2. Name the project "CheckboxTest".

3. Replace the MainWindow.xaml file contents with the XAML below:

<Window
    x:Class="CheckboxTest.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:CheckboxTest"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d"
    Title="ContentDialog Focus Test">

    <StackPanel Orientation="Horizontal" HorizontalAlignment="Center" VerticalAlignment="Center">
        <Button Name="ShowDialogButton" Content="Show Dialog" Click="ShowDialogButton_Click" />
        <ContentDialog
            x:Name="DeleteConfirmationDialog"
            Title="Delete file"
            PrimaryButtonText="Move to Recycle Bin"
            CloseButtonText="Cancel"
            DefaultButton="Close">
            <StackPanel VerticalAlignment="Stretch" HorizontalAlignment="Stretch" Spacing="12">
                <TextBlock TextWrapping="Wrap" Text="Are you sure you want to move file 'somefile.jpg' to the Recycle Bin?" />
                <CheckBox x:Name="DeleteDontAskCheckbox" Content="Don't ask me again" />
            </StackPanel>
        </ContentDialog>
    </StackPanel>
</Window>

4. Replace the MainWindow.xaml.cs file code with:

using System;
using System.Threading.Tasks;
using Microsoft.UI.Xaml;
using Microsoft.UI.Xaml.Controls;
using Microsoft.UI.Xaml.Input;

namespace CheckboxTest;

public sealed partial class MainWindow : Window
{
    public MainWindow()
    {
        this.InitializeComponent();
        this.Content.KeyUp += Content_KeyUp;
    }

    private async void Content_KeyUp(object sender, KeyRoutedEventArgs e)
    {
        if (e.Key == Windows.System.VirtualKey.Delete)
        {
            if (await OpenDeleteDialog() == ContentDialogResult.Primary)
            {
                // ... do delete stuff
            }
        }
    }

    private async void ShowDialogButton_Click(object sender, RoutedEventArgs e)
    {
        if (await OpenDeleteDialog() == ContentDialogResult.Primary)
        {
            // ... do delete stuff
        }
    }

    private async Task<ContentDialogResult> OpenDeleteDialog()
    {
        DeleteConfirmationDialog.XamlRoot = Content.XamlRoot;
        return await DeleteConfirmationDialog.ShowAsync();
    }
}

5. Run the project and click the "Show Dialog" button. Observe that the dialog is shown with no focus highlight present on the checkbox control:

6. Close the dialog by pressing Enter or selecting the "Cancel" button.

7. Press Delete. Observe that the dialog is shown with the first interactive element highlighted as the focussed control:

Expected behavior

The display of the focus highlight should be consistent, i.e. independent of the method used to show the ContentDialog. I suggest not showing the highlight until the user uses Tab to move the focus around the dialog's controls.

Screenshots

No response

NuGet package version

None

Windows version

Windows 11 (24H2): Build 26100

Additional context

Additional context may be found on my StackOverflow question here: https://stackoverflow.com/questions/79376328/winui-3-how-to-set-focus-to-a-contentdialog-button/79382988