WinRT getting callbacks to Win32 application

Question

I am having problem getting callbacks from WinRT to Win32 application.

This code builds...... but I never get the callback even if I toggle HighContrast on and off in the control panel.

Bellow is my code, which builds and does not crash when I run it, but the OutputDebugString inside of the callback I never get.

Is there something I should be doing differently ?

OutputDebugStringW(L"Adding callback");

   settings->add_HighContrastChanged(Microsoft::WRL::Callback<ABI::Windows::Foundation::ITypedEventHandler< abi_vm::AccessibilitySettings*, IInspectable*>>
    (
        [](auto&& s, IInspectable*) -> HRESULT
         {
            OutputDebugStringW(L"High contrast changed");
            return 0;
         }
        ).Get(), 
       &token);

Thanks.

Answer 1

On my OS (Windows 10 21H1), I only get this event with Packaged apps, not Desktop apps (while other events work)

For example in UWP, in the MainPage class :

 hcChangedRevoker = accSettings.HighContrastChanged(winrt::auto_revoke, [this](winrt::Windows::UI::ViewManagement::AccessibilitySettings const&, winrt::Windows::Foundation::IInspectable const&)
            {
                // code...
            });

with

 Windows::UI::ViewManagement::AccessibilitySettings accSettings;
 Windows::UI::ViewManagement::AccessibilitySettings::HighContrastChanged_revoker hcChangedRevoker;