ExtendsContentIntoTitleBar causes incorrect cursor events, button hover flickering, and click issues

[DavidRufino]

Describe the bug

When ExtendsContentIntoTitleBar = true is set on both the main window and any child windows, certain interactions cause incorrect cursor event processing.

Not reproducible in:
Microsoft.WindowsAppSDK 1.5.250108004

PoitnerFlickeringIssue

Steps to reproduce the bug

1. Create a child window with ExtendsContentIntoTitleBar = true
2. You can reproduce the issue by either minimizing the child window, or by moving the mouse cursor upward — starting from inside the child window, passing through its title bar, and continuing into the main window.
3. Interact with UI elements in the main window

Expected behavior

Button hover states flickering;
Tooltips dont show;
MenuFlyoutSubItem closing;
Click events not firing correctly;

Screenshots

unknown_2025.04.25-18.24.mp4

NuGet package version

WinUI 3 - Windows App SDK 1.7.1: 1.7.250401001

Windows version

Windows 11 (24H2): Build 26100

Additional context

You can consistently reproduce the issue using the WinUI 3 Gallery app:

1. Navigate to: Windowing > Multiple windows
2. Click Create new Window
3. You can reproduce the issue by either minimizing the child window, or by moving the mouse cursor upward — starting from inside the child window, passing through its title bar, and continuing into the main window.

Observe button hover flickering and click issues in the main window

[DHancock]

Looks like another incarnation of #10067 that I opened 6 months ago. Eventually a microsoft manager will realise that there is little point adding shiny new features to the sdk if the base line quality is so poor that nobody can release anything using it.

[wbokkers]

Our customers have exactly this issue. I can reproduce using the information David supplied.
What is worse: clicks/taps do often not register. Customers are complaining that clicking do not take effect.

Please fix this asap!
I can reproduce this in version 1.7.1 and 1.7.2

[DavidRufino]

After researching the issue, I created a workaround.

Basically, if you want a custom title bar, don’t use Window.ExtendsContentIntoTitleBar or Window.SetTitleBar.

public sealed partial class MainWindow : Window
{
    public MainWindow()
    {
        this.InitializeComponent();

        // Not recommended:
        this.ExtendsContentIntoTitleBar = true;
        this.SetTitleBar(AppTitleBar);
    }
}

Use the AppWindow.TitleBar:

var titleBar = this.AppWindow.TitleBar;
titleBar.ExtendsContentIntoTitleBar = true;

Then, disable the default title bar buttons (Minimize, Maximize, Close):

Presenter.IsResizable = true;
Presenter.SetBorderAndTitleBar(true, false);

and handle the drag area and top resize manually:

this._newWndProc = new WndProcDelegate(CustomWndProc);
this._prevWndProc = SetWindowLongPtr(this.HWnd, GWLP_WNDPROC, this._newWndProc);

After applying this approach, I haven’t been able to reproduce the issue anymore.

See the GitHub repository:
github.com/DavidRufino/PoitnerFlickering-Workaround

[wbokkers]

@codendone Any news on this and the related issues? Will it be fixed in the upcoming release?