COM Inheritance in C Win32.

WinMain.c

#include <initguid.h>
#include <windows.h>
#include <shobjidl.h>

void $(const char *format, ...)
{
    va_list ArgList = NULL;
    va_start(ArgList, format);
    CHAR szOutput[1025] = {};
    WriteFile(GetStdHandle(STD_OUTPUT_HANDLE), szOutput, wvsprintfA(szOutput, format, ArgList), NULL, NULL);
    va_end(ArgList);
}

HRESULT QueryInterface(IAppVisibilityEvents *This, REFIID riid, void **ppvObject)
{
    return RtlCompareMemory(riid, &IID_IAppVisibilityEvents, sizeof(IID)) == sizeof(IID) ||
                   RtlCompareMemory(riid, &IID_IUnknown, sizeof(IID)) == sizeof(IID)
               ? !(*ppvObject = This)
               : E_NOINTERFACE;
}

ULONG _(IAppVisibilityEvents *_)
{
    return 0;
}

HRESULT AppVisibilityOnMonitorChanged(IAppVisibilityEvents *This, HMONITOR hMonitor,
                                      MONITOR_APP_VISIBILITY previousMode, MONITOR_APP_VISIBILITY currentMode)
{
    static INT _ = 0;
    $("AppVisibilityOnMonitorChange: %d\n", ++_);
    return S_OK;
}

HRESULT LauncherVisibilityChange(IAppVisibilityEvents *This, WINBOOL currentVisibleState)
{
    static INT _ = 0;
    $("LauncherVisibilityChange: %d\n", ++_);
    return S_OK;
}

int mainCRTStartup()
{
    CoInitialize(NULL);

    IAppVisibility *pAppVisibility = NULL;
    CoCreateInstance(&CLSID_AppVisibility, NULL, CLSCTX_INPROC_SERVER, &IID_IAppVisibility, (LPVOID *)&pAppVisibility);
    pAppVisibility->lpVtbl->Advise(
        pAppVisibility,
        &((IAppVisibilityEvents){.lpVtbl = &((IAppVisibilityEventsVtbl){
                                     QueryInterface, _, _, AppVisibilityOnMonitorChanged, LauncherVisibilityChange})}),
        &((DWORD){}));

    MSG _ = {};
    while (GetMessageW(&_, NULL, 0, 0))
        DispatchMessageW(&_);
    return 0;
}