https://learn.microsoft.com/en-us/windows/windows-app-sdk/api/winrt/microsoft.ui.xaml.controls.appbarseparator?view=windows-app-sdk-2.0
AppBarSeparator Class (Microsoft.UI.Xaml.Controls) - Windows App SDK | Microsoft Learn
Represents a line that separates items in an AppBar or CommandBar.
windows appclassmicrosoftuixaml