https://learn.microsoft.com/en-us/windows/windows-app-sdk/api/winrt/microsoft.ui.xaml.controls.primitives.flyoutbase.lightdismissoverlaymode?view=windows-app-sdk-1.8
FlyoutBase.LightDismissOverlayMode Property (Microsoft.UI.Xaml.Controls.Primitives) - Windows App...
Gets or sets a value that specifies whether the area outside of a light-dismiss UI is darkened.
propertymicrosoftuixamlcontrols