[BUG] Popup not centered with FlyoutBehaviour.Locked on macOS

[mpiechocki]

Is there an existing issue for this?

• I have searched the existing issues

Did you read the "Reporting a bug" section on Contributing file?

• I have read the "Reporting a bug" section on Contributing file: https://github.com/CommunityToolkit/Maui/blob/main/CONTRIBUTING.md#reporting-a-bug

Current Behavior

I have a simple Flyout Shell that has FlyoutBehaviour set to Locked and PresentationMode set to NotAnimated. When I try to open a Popup from ShellContent, it is not appearing centered over the whole app and not even centered over the FlyoutItem contents:

The Popup has VerticalOptions and HorizontalOptions set to Center:

<toolkit:Popup xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
               xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
               xmlns:toolkit="http://schemas.microsoft.com/dotnet/2022/maui/toolkit"
               x:Class="MauiApp1.NewPopup"
               VerticalOptions="Center"
               HorizontalOptions="Center">

    <VerticalStackLayout>
        <Label Text="This is a very important message!"/>
    </VerticalStackLayout>

</toolkit:Popup>

I'm on macOS, using VS Code and .net9.0-maccatalyst, with CommunityToolkit.Maui 11.1.0 and Microsoft.Maui.Contols 9.0.30.

Expected Behavior

I would expect the ability to open the popup centered over the whole application, but if that's not possible, to at least be centered over the contents of the current page.

Steps To Reproduce

1. Open the reproduction project
2. Click on Click me button on the opened page

Link to public reproduction project repository

https://github.com/mpiechocki/MauiPopup

Environment

- .NET MAUI CommunityToolkit: 11.1.0
- OS: macOS 15.3
- .NET MAUI: 9.0.14

Anything else?

No response