How can I hide the dates that are not part of the current month in the CalendarView control in WinUI 3?

I am using the CalendarView control in my WinUI 3 project. I want to hide the out-of-scope dates. I didn’t find any property for this. I can set the OutOfScopeForeground to match the calendar background, but that only hides the dates visually. I can still select them.

I have marked the out-of-scope dates in the image below. How can I disable them?

I guess, you'll need to create a custom (templated) control, something like this:

public partial class CalendarViewEx : CalendarView
{
    public CalendarViewEx()
    {
        this.DefaultStyleKey = typeof(CalendarViewEx);
        Loaded += CalendarViewEx_Loaded;
        Unloaded += CalendarViewEx_Unloaded;
    }

    private long HeaderButtonContentChangeToken { get; set; }

    private Button? HeaderButton { get; set; }

    private void CalendarViewEx_Loaded(object sender, RoutedEventArgs e)
    {
        if (GetTemplateChild("HeaderButton") is Button headerButton)
        {
            HeaderButton = headerButton;
            HeaderButtonContentChangeToken = HeaderButton.RegisterPropertyChangedCallback(Button.ContentProperty, OnHeaderButtonContentPropertyChanged);
        }

        RefreshCalenderViewDayItems();
    }

    private void CalendarViewEx_Unloaded(object sender, RoutedEventArgs e)
    {
        if (HeaderButton is not null)
        {
            HeaderButton.UnregisterPropertyChangedCallback(Button.ContentProperty, HeaderButtonContentChangeToken);
            HeaderButton = null;
        }
    }

    private void OnHeaderButtonContentPropertyChanged(DependencyObject sender, DependencyProperty dp)
    {
        RefreshCalenderViewDayItems();
    }

    private void RefreshCalenderViewDayItems()
    {
        if (HeaderButton?.Content is not string headerText)
        {
            return;
        }

        // Removes hidden unicode characters.
        var cleanedHeaderText = new string([.. headerText.Where(c => !char.IsControl(c) && CharUnicodeInfo.GetUnicodeCategory(c) != UnicodeCategory.Format)]);

        // You might need to modify this according to the language.
        if (!DateTime.TryParseExact(cleanedHeaderText, "MMMM yyyy", CultureInfo.InvariantCulture, DateTimeStyles.None, out var headerDate))
        {
            System.Diagnostics.Debug.WriteLine($"Failed to parse header text: {headerText}");
            return;
        }

        foreach (CalendarViewDayItem item in this.FindDescendants().OfType<CalendarViewDayItem>())
        {
            item.Visibility = item.Date.Month != headerDate.Month ? Visibility.Collapsed : Visibility.Visible;
        }
    }
}

<Style TargetType="local:CalendarViewEx" BasedOn="{StaticResource DefaultCalendarViewStyle}" />

• FindDescendants() comes from the CommunityToolkit.WinUI.Extensions NuGet package.