Close button flickers on hover and sometimes cannot be clicked of Window

Describe the bug

https://github.com/user-attachments/assets/4b40b8c8-007f-436a-bc98-c45661cece27

The issue can now be consistently reproduced.

When hovering the mouse cursor near the close button (top-right corner) of the window, the button flickers and sometimes becomes unclickable, as shown in the attached video.

To Reproduce

1. Create a new project
2. Select WPF UI – Fluent Navigation template
3. Place the attached XAML and C# files under:
   Views / Windows

TestWindow.zip

4. Add the following method to SettingsViewModel.cs:

[RelayCommand]
private void OnTestWindow()
{
    var testWindow = new Views.Windows.TestWindow()
    {
        Owner = App.Current.MainWindow
    };
    testWindow.ShowDialog();
}

5. Run the application
6. Click the Settings button
7. Click the Test Window button
8. When the window appears, move the mouse cursor near the close button

Expected behavior

• The close button should remain stable on hover
• The button should always be clickable

Screenshots

No response

OS version

Windows 11 Pro

.NET version

.NET 10

WPF-UI NuGet version

4.1.0 - 4.2.0

Additional context

If it helps, I can upload the full project files for investigation.
Please let me know if that would be useful.

UiDesktopApp3.zip

Reproduce the flicker using the WPF UI – Fluent Navigation template, the attached TestWindow files under Views/Windows, and the SettingsViewModel.cs command. Start by running the provided reproduction project on Windows 11 with WPF-UI 4.1.0–4.2.0; done means the close button remains stable near hover and is always clickable.