Cannot run sample program. VirtualDesktopProvider does not exist.

[JimF42]

I am trying to run the sample program, but the compiler is telling me that VirtualDesktopProvider does not exist, so it cannot even compile VirtualDesktopProvider.Default.Initialize();

try
{
    await VirtualDesktopProvider.Default.Initialize();
}
catch (Exception ex)
{
    MessageBox.Show(ex.Message, "Failed to initialize.");
}

Has something changed?