Use global menu and custom window border when platform supports global menu exporting

[kekekeks]

Maximized window of adapted application:

Maximized window of Jaya:

[waliarubal]

@kekekeks Do you have any example pointing such implementation? I will be glad to implement it. And thanks for taking a look at my project.

[kekekeks]

Recent Avalonia builds have support for global menu integration. Such menu can be declared like this: https://github.com/AvaloniaUI/Avalonia/blob/7dc95d5644bd3b14d2760cb664599e24fc239344/samples/ControlCatalog/MainWindow.xaml#L12

There is also NativeMenu.IsMenuExported attached property that becomes true when there is platform support for the global menu bar.

For Linux the support for global menu can be enabled like this: https://github.com/AvaloniaUI/Avalonia/blob/7dc95d5644bd3b14d2760cb664599e24fc239344/samples/ControlCatalog.NetCore/Program.cs#L61