function CallCBTProc(Code: Integer; wParam: WPARAM; lParam: LPARAM): LRESULT; stdcall;
begin
 case Code of
   HCBT_CREATEWND: ...
   HCBT_ACTIVATE: ...
   HCBT_SYSCOMMAND:
     if (wParam = SC_MOUSEMENU) then
       GetMenuItem(Point(LOWORD(lParam), HIWORD(lParam)));
 end;
 Result := CallNextHookEx(hCBTHook, Code, wParam, lParam);
end;

procedure GetMenuItem(Pt: TPoint);
var
 hMainMenu: HMENU;
 MII: TMenuItemInfo;
 ItemPos: Integer;
begin
 hMainMenu := GetMenu(hWnd);
 ItemPos := MenuItemFromPoint(hWnd, hMainMenu, Pt);
 WriteFileInfo('@ItemPos: ' + IntToStr(ItemPos));
 WriteFileInfo('@X,Y: ' + IntToStr(Pt.X) + ',' + IntToStr(Pt.Y));
 ZeroMemory(@MII, SizeOf(MII));
 MII.cbSize     := SizeOf(MII);
 MII.fMask      := MIIM_SUBMENU;
 if GetMenuItemInfo(hMainMenu, SC_RQM, False, MII) then begin
   ItemPos := MenuItemFromPoint(hWnd, MII.hSubMenu, Pt);
   WriteFileInfo('ItemPos: ' + IntToStr(ItemPos));
   if GetMenuItemInfo(MII.hSubMenu, SC_RQM, False, MII) then
     WriteFileInfo('ItemId: ' + IntToStr(MII.wID));
 end;
end;