https://learn.microsoft.com/en-us/windows/windows-app-sdk/api/winrt/microsoft.ui.xaml.uielement.gettingfocus?view=windows-app-sdk-1.5
UIElement.GettingFocus Event (Microsoft.UI.Xaml) - Windows App SDK | Microsoft Learn
Occurs before a UIElement receives focus. This event is raised synchronously to ensure focus isn't moved while the event is bubbling.
windows appeventmicrosoftuixaml