romrepomgr/RomRepoMgr/App.xaml

<Application xmlns="https://github.com/avaloniaui"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:local="clr-namespace:RomRepoMgr"
             x:Class="RomRepoMgr.App">
    <Application.DataTemplates>
        <local:ViewLocator />
    </Application.DataTemplates>
    <Application.Styles>
        <FluentTheme />
        <StyleInclude Source="avares://Avalonia.Controls.DataGrid/Themes/Fluent.xaml"/>
    </Application.Styles>
    <NativeMenu.Menu>
        <NativeMenu>
            <NativeMenuItem Header="_About"
                            Click="OnAboutClicked" />
            <NativeMenuItem Header="_Preferences"
                            Click="OnPreferencesClicked" />
            <NativeMenuItem Header="_Quit"
                            Click="OnQuitClicked" />
        </NativeMenu>
    </NativeMenu.Menu>
</Application>