win32: menu and WM_SYSCOMMAND... what i'm doing wrong with mouse click?

[Cambalinho]

i added a menu item on System Menu:

HINSTANCE hinstance=GetModuleHandle(NULL);

LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
    static UINT ID=0;
    static HMENU mnTopMost=NULL;
    static HMENU mnSelTopMost=NULL;

    switch(msg)
    {
        case WM_CLOSE:
        {
            DestroyWindow(hwnd);
        }
        break;
        case WM_CREATE:
        {
            mnTopMost=GetSystemMenu(hwnd,FALSE);
            ID=GetMenuItemCount(mnTopMost);
            AppendMenu(mnTopMost, MF_STRING, ID, "Top Most");
        }
        break;
        case WM_SIZE:
        case WM_SIZING:
        {
            RECT a;
            GetClientRect(hwnd,&a);
            HWND edit=FindWindowEx(hwnd,NULL,"edit",NULL);
            SetWindowPos(edit,0,0,0,a.right,a.bottom,SWP_NOMOVE | SWP_NOZORDER | SWP_NOREPOSITION);
        }
        break;

        case WM_INITMENUPOPUP:
        {
            mnSelTopMost=(HMENU)wParam;
            return DefWindowProc(hwnd, msg, wParam, lParam);
        }
        break;
        case WM_SYSCOMMAND:
        {
            if (GetMenuState(mnSelTopMost,ID,MF_BYPOSITION)!=0xFFFFFFFF)
            {
                MessageBox(NULL,"clicked","hey",MB_OK);
            }
            mnSelTopMost=NULL;
            return DefWindowProc(hwnd, msg, wParam, lParam);
        }
        break;
        default:
            return DefWindowProc(hwnd, msg, wParam, lParam);
    }
    return 0;
}

the menu item is showed correctly. my problem is with WM_SYSCOMMAND :(
or the click works for all items or don't works :(
please someone can correct me? :(
these don't make sence to me... i'm trying without sucess :(

[Cambalinho]

after reading these i found it:
https://www-user.tu-chemnitz.de/~heha/petzold/ch10c.htm

the wParam give me the menu ID. but i didn't find how can i get the menu handle :(
(i had tryied the lParam, but don't works... that's why i continue with WM_INITMENUPOPUP, for get the menu handle.
but i will continue waiting for an answer.
from MSDN: https://msdn.microsoft.com/en-us/library/windows/desktop/ms646360%28v=vs.85%29.aspx
even the ID, i can't find it :(

[E0p9LyTq]

You don't need the menu handle when dealing with your custom system menu items being selected, the handle is only needed when adding custom menu items:

// some global defines for the system menu addons
#define IDM_SYS_ABOUT   1
#define IDM_SYS_HELP    2
#define IDM_SYS_REMOVE  3

// ....

LRESULT CALLBACK WndProc (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
   switch (message)
   {
   case WM_CREATE:
   {
      HMENU hMenu = GetSystemMenu(hwnd, FALSE);

      AppendMenu(hMenu, MF_SEPARATOR, 0, NULL);
      AppendMenu(hMenu, MF_STRING, IDM_SYS_ABOUT, TEXT("About..."));
      AppendMenu(hMenu, MF_STRING, IDM_SYS_HELP, TEXT("Help..."));
      AppendMenu(hMenu, MF_STRING, IDM_SYS_REMOVE, TEXT("Remove Additions"));
      break;
   }

   case WM_SYSCOMMAND:
      switch (LOWORD (wParam))
      {
      case IDM_SYS_ABOUT:
         MessageBox(hwnd, TEXT("A Poor-Person's Menu Program\n(c) Me, 2016"),
                    szAppName, MB_OK | MB_ICONINFORMATION);
         return 0;

      case IDM_SYS_HELP:
         MessageBox(hwnd, TEXT ("Help not yet implemented!"),
                    szAppName, MB_OK | MB_ICONEXCLAMATION);
         return 0;

      case IDM_SYS_REMOVE:
         GetSystemMenu(hwnd, TRUE);
         return 0;
      }
      break ;

   case WM_DESTROY:
      PostQuitMessage(0);
      return 0;
   }
   return DefWindowProc(hwnd, message, wParam, lParam);
}