Int 2F Fn 1684  - Ms Windows - Postmsg - Get Api Entry Point               [W]

   AX = 1684h
   BX = 4321h (virtual device ID for POSTMSG device) (see #2329)
   ES:DI = 0000h:0000h

Return: ES:DI -> VxD API entry point (see #2399,#2401)
         0000h:0000h if the VxD does not support an API

(Table 2399)
Call POSTMSG protected-mode entry point with:
   AX = window handle
   CX:BX -> callback procedure (see #2400)

Return: nothing

Note:  this call registers a WinApp with the VxD; the callback must be in a
     fixed, non-discardable code segment

See Also: #2401,#2402

(Table 2400)
Values POSTMSG callback routine is called with:
   STACK:  DWORD   "lParam" parameter from DOSApp
       WORD    "wParam" parameter from DOSApp
       WORD    Windows message number (WM_USER + 100h)
       WORD    registered HWND

(Table 2401)
Call POSTMSG V86-mode entry point with:
   BX = wParam value to pass to protected-mode callback
   DX:AX = lParam value to pass to protected-mode callback

Return: CF clear if successful
   CF set on error (no WinApp registered)

See Also: #2399