TitleBar title doesn't propagate to window

[dotMorten]

Describe the bug

When setting the Title and subtitle on the titlebar control, the actual window's title stays "WinUI Desktop".
This means when you hover on the taskbar, it'll still show the default "WinUI Desktop", and if you enable narrator the wrong window title will be spoken when the window activates

Steps to reproduce the bug

1. Create a window with the new TitleBar
2. Set the Title and subtitle of the TitleBar
3. Run the app and hover on the task bar. Notice the window title:
   
4. Start Narrator and activate the window. Notice that the narrator will say "WinUI Desktop", and not the TitleBar's Title.

Expected behavior

The correct taskbar title should be set.

Screenshots

No response

NuGet package version

WinUI 3 - Windows App SDK 1.7.1: 1.7.250401001

Windows version

Windows 11 (24H2): Build 26100

Additional context

As a workaround you can do something ugly like this, but this really shouldn't be necessary and the issue is easily overlooked and leads to accessibility issues if you forget to add something like this:

        public MainWindow()
        {
            this.InitializeComponent();
#region Workaround for https://github.com/microsoft/microsoft-ui-xaml/issues/10557
            MainWindowTitleBar.RegisterPropertyChangedCallback(Microsoft.UI.Xaml.Controls.TitleBar.TitleProperty, (s, e) => UpdateWindowTitle() );
            MainWindowTitleBar.RegisterPropertyChangedCallback(Microsoft.UI.Xaml.Controls.TitleBar.SubtitleProperty, (s, e) => UpdateWindowTitle());
            UpdateWindowTitle();
#endregion
        }

        private void UpdateWindowTitle()
        {
            // This ensures the Title on the taskbar matches the window title, and narrator will read the correct title
            this.Title = MainWindowTitleBar.Title + " - " + MainWindowTitleBar.Subtitle;
        }

[Zakariathr22]

I can't reproduce this issue with the introduced code, can you please provide more information?

public sealed partial class MainWindow : Window
{
    public MainWindow()
    {
        this.InitializeComponent();
        MainWindowTitleBar.RegisterPropertyChangedCallback(TitleBar.TitleProperty, (s, e) => UpdateWindowTitle());
        MainWindowTitleBar.RegisterPropertyChangedCallback(TitleBar.SubtitleProperty, (s, e) => UpdateWindowTitle());
        UpdateWindowTitle();
    }

    private void UpdateWindowTitle()
    {
        // This ensures the Title on the taskbar matches the window title, and narrator will read the correct title
        this.Title = MainWindowTitleBar.Title + " - " + MainWindowTitleBar.Subtitle;
    }
}

<TitleBar x:Name="MainWindowTitleBar" Title="title" Subtitle="subtitle" />

[dotMorten]

@Zakariathr22 The above code is workaround that works around the issue. So if you apply the workaround you won't reproduce it :-)

[Zakariathr22]

Oh, I get you now 😆

In my opinion, it's not good practice for changing a control's property to also alter window properties.

Actually, I don't think the current approach to setting the window title is ideal either, as having both Window.Title and AppWindow.Title is redundant and potentially confusing if not managed carefully.

[Jay-o-Way]

When setting the Title and subtitle on the titlebar control, the actual window's title stays "WinUI Desktop".

@dotMorten correct me if I'm wrong, but... I think the TitleBar is mostly a "visual", page-level control, just like many other controls. Creating a normal TextBlock wouldn't change the app window's title either. Can you show me where it says that this must work, like you expect it to?

[Balkoth]

The TitleBar is not a page-level control, it's a window-level control. It controls what happens with the window hosting other controls. If the title of the window changes, so has the title in the TitleBar.

Se here it always talks about window title:

[Jay-o-Way]

@Balkoth the (new) TitleBar is absolutely very much a XAML control. Note how @dotMorten uses the word "control" and he knows what he means.
The text you show does say "window", but this is mostly means the UI window. Visually. Please share the link to the page you found, and compare https://learn.microsoft.com/windows/windows-app-sdk/api/winrt/microsoft.ui.xaml.controls.titlebar?view=windows-app-sdk-1.7
In the Xaml TitleBar control you can't (easily) set the text style.

[Balkoth]

I don't understand what you are talking about. Yes the TitleBar is a control. Does it matter? No. Did i say something else? No. Window title a.k.a. window text is not a new concept (https://learn.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-setwindowtexta).

This is the link to the previous screenshot:
https://learn.microsoft.com/en-us/windows/apps/design/basics/titlebar-design

[Jay-o-Way]

@Balkoth yes it does matter. The page you found is meant for when designer "had to" create a custom (aka modern) titlebar. Note that this usually is a grid, with icon and text controls etc. All the layout had to be manually coded.

Now, please read the doc that I linked to in my previous comment! [edit: or https://learn.microsoft.com/en-us/windows/apps/design/controls/title-bar] Hopefully you'll understand a bit more then.

[Balkoth]

You said it does matter that the TitleBar is a control, but that’s not in dispute. I never claimed it wasn’t a control — in fact, I explicitly acknowledged that it is. My point is that whether it’s a control or not is irrelevant to the concept of setting the window title (i.e., the window text), which has been a standard part of the Windows API for decades.

The link I provided — SetWindowTextA — demonstrates that the window title is a property of the window itself, not something inherently tied to whether the title bar is custom-drawn or not. That API works regardless of whether you're using a classic title bar or a custom one built with XAML or WinUI.

Yes, when you create a custom title bar, you’re responsible for laying out the controls (icon, text, buttons, etc.) manually — that’s well understood. But that doesn’t negate the fact that the concept of a window title is not new, nor is it dependent on the implementation details of the title bar.

So again: the existence of a custom title bar doesn’t change the fundamental concept of a window title.