[regression/8.0.0-preview.4.8333] Full-screening a window no longer removes its title-bar

[aidan-bailey]

Description

When fullscreening a window in 8.0.0-preview.4, an empty title-bar remains, e.g.

On 7, this behaves appropriately, e.g.

Steps to Reproduce

1. Create a new MAUI App template (8.0.0 preview).
2. Replace MainPage = new Shell(); with MainPage = new MainPage(); in App.xaml.cs.
3. Add the following code to the CreateMauiApp method in MauiProgram.cs:

#if WINDOWS
        builder.ConfigureLifecycleEvents(events => {
            // Make sure to add "using Microsoft.Maui.LifecycleEvents;" in the top of the file 
            events.AddWindows(windowsLifecycleBuilder => {
                windowsLifecycleBuilder.OnWindowCreated(window => {
                    window.ExtendsContentIntoTitleBar = false;
                });
            });
        });
#endif

4. Replace the content of OnCounterClicked in MainPage.xaml.cs with:

#if WINDOWS
        var window = Window.Handler.PlatformView as MauiWinUIWindow;
        var handle = WinRT.Interop.WindowNative.GetWindowHandle(window);
        var id = Microsoft.UI.Win32Interop.GetWindowIdFromWindow(handle);
        var appWindow = Microsoft.UI.Windowing.AppWindow.GetFromWindowId(id);

        switch (appWindow.Presenter) {
            case Microsoft.UI.Windowing.OverlappedPresenter overlappedPresenter:
                if (overlappedPresenter.State == Microsoft.UI.Windowing.OverlappedPresenterState.Maximized) {
                    overlappedPresenter.SetBorderAndTitleBar(true, true);
                    overlappedPresenter.Restore();
                } else {
                    overlappedPresenter.SetBorderAndTitleBar(false, false);
                    overlappedPresenter.Maximize();
                }

                break;
        }
#endif

5. Change the background colour of the ScrollView in MainPage.xaml so you can see the background of the page clearer:

...
<ScrollView BackgroundColor="Red">
...

6. Launch app and click the button to see the title-bar still existing with just the top-right buttons disappearing.

Link to public reproduction project repository

https://github.com/aidanjbailey/Maui8FullscreenTest

Version with bug

8.0.0-preview.4.8333

Last version that worked well

7.0.86

Affected platforms

Windows

Affected platform versions

Windows SDK 10.0.19041.0

Did you find any workaround?

I have not been able to find a workaround.

Relevant log output

No response

[XamlTest]

Verified this on Visual Studio Enterprise 17.7.0 Preview 4.0. Repro on Windows 11 .NET 8 with below Project:
15676.zip

[samhouts]

I can confirm that the titlebar is different between NET 7 and NET 8 (in NET 7, the buttons are still there), but I did not ever see the titlebar disappear in any version, so it is unclear if this is a regression and/or when the regression occurred.