include 'J:\fasmw16727\INCLUDE\win32ax.inc'
text:
invoke FindWindow,0,"World of Warcraft"
test eax,eax
jz err2
mov edi,eax
post:   invoke PostMessage,edi,256,"a",0
        test eax,eax
        jz err
        invoke PostMessage,edi,257,"a",0
        invoke Sleep,1000
        jmp post
err:    invoke MessageBox,0,"Can't post message","Err",0
        xor esp,esp
err2:   invoke MessageBox,0,"Window not found","Err",0
        xor esp,esp
.end text    

include 'J:\fasmw16727\INCLUDE\win32ax.inc'
text:
invoke FindWindow,0,"Untitled - Notepad"
test eax,eax
jz err2
invoke GetDlgItem,eax,0x0000000F
test eax,eax
jz err2
mov edi,eax
post:   invoke PostMessage,edi,256,"a",0
        test eax,eax
        jz err
        invoke PostMessage,edi,257,"a",0
        invoke Sleep,1000
        jmp post
err:    invoke MessageBox,0,"Can't post message","Err",0
        xor esp,esp
err2:   invoke MessageBox,0,"Window not found","Err",0
        xor esp,esp
.end text    

invoke PostMessage,edi,256,0x61,0    

include 'J:\fasmw16727\INCLUDE\win32ax.inc'
a dw "a",0
text:
invoke FindWindow,0,"Untitled - Notepad"
test eax,eax 
jz err2 
invoke GetDlgItem,eax,0x0000000F
test eax,eax 
jz err2
mov edi,eax
post:   invoke PostMessage,edi,256,[a],0
        test eax,eax 
        jz err 
        invoke PostMessage,edi,257,[a],0
        invoke Sleep,1000 
        jmp post 
err:    invoke MessageBox,0,"Can't post message","Err",0 
        xor esp,esp 
err2:   invoke MessageBox,0,"Window not found","Err",0 
        xor esp,esp 
.end text    

You should really show your message retrieval loop to show the problem.

invoke PostMessage,edi,WM_KEYDOWN,VK_A,1
...
invoke PostMessage,edi,WM_KEYUP,VK_A,1    

        include "WIN32AX.INC"

        .code
start:  invoke  FindWindow, 0, "Untitled - Notepad"
        invoke  GetDlgItem, eax, 15
        invoke  PostMessage, eax, WM_CHAR, ('B'), 0
        ret

        .end    start    

actually focusing them isn't an option since with full screen windows it takes a long time to focus them and then give focus back to whatever was up before..

You should ideally use keybd_event to send keystrokes to windows. Look up the MS documentation for it.

Plus, if you still want to use WM_KEYUP/DOWN then you should also use the proper scan code and the transition codes in the high order bits of lParam. Look up the proper MS documentation for how to use it properly.

Azu,

May be single WM_CHAR will be enough?

Code:

        include "WIN32AX.INC"

        .code
start:  invoke  FindWindow, 0, "Untitled - Notepad"
        invoke  GetDlgItem, eax, 15
        invoke  PostMessage, eax, WM_CHAR, ('B'), 0
        ret

        .end    start    

        include "WIN32AX.INC"

        .code
start:  invoke  FindWindow, NULL, "Untitled - Notepad"
        invoke  FindWindowEx, eax, NULL, "EDIT", NULL
        invoke  PostMessage, eax, WM_CHAR, ('C'), 0
        ret

        .end    start    

All programs use a different set of controls, and the windows keyboard record/playback only works on the active window. I've never seen a universal way to send events to non-active windows. I would be very interested in such a discovery as long as it doesn't involve rewriting a large chunk of windows, or injecting code into another process.

Two of the most difficult functions to overcome when trying to emulate keystrokes are GetAsyncKeyState and GetKeyboardState. Many games like to use these functions.

we have DirectInput also…

Azu,

This is by design. DispatchMessage() provide common code for message dispatching (i.e. determine which window gets what message from thread message queue). Your program could handle this on its own, but you seldom encounter GUI program without GetMessage()/TranslateMessage()/DispatchMessage() loop of some kind.

As I've already said, you can directly send messages to inactive window, thus bypassing message pump and DispatchMessage(). It's WndProc() will handle them as usual (provided that window procedure is not state-aware ). The hard part is to determine to which window you have to send them and find it in process' windows hierarchy at run-time.