Tested this demo in Win10 1803 version, seems it can not work well, there are some exceptions.
one exception is "Windows.Graphics.Capture.GraphicsCaptureItem" is not registered.
After checking the notes of "Windows.UI.Composition-Win32-Samples/dotnet/WPF/ScreenCapture/", the demo need run in win 10 1903 or higher version. So close this issue now.
Tested this demo in Win10 1803 version, seems it can not work well, there are some exceptions. one exception is "Windows.Graphics.Capture.GraphicsCaptureItem" is not registered.
Can someone help explain the reason?