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[therealchriswoodward]

[DarranRowe]

What documentation gave this code? I ask because it is outright incorrect if you are trying to use it with WinUI 3. There are three major things in this which are wrong.

1. CoreApplication is documented to only have the Properties property available in desktop applications.
   "This API is supported in Universal Windows Platform apps only, except for the Properties property, which is always available."
   By extension, this means that CoreApplication.MainView will always fail.
2. CoreDispatcher is documented to be outright unavailable in desktop applications. What's more, CoreDispatcher isn't a dispatcher queue. For WinUI 3, you would be using the Windows App SDK DispatcherQueue. This can be obtained from Microsoft.UI.Xaml.Window.DispatcherQueue.
3. The pickers must use be properly initialised in the desktop environment. This again is documented. In the desktop environment, you must set a desktop window as the parent of the picker, which is what that IInitializeWithWindow does. Be aware that you must obtain the window handle from a class that derives from Microsoft.UI.Xaml.Window.
   And just to clarify, WinUI 3 applications only run in the desktop environment. The library and packaging may make them look like they are UWP, but they are not.