format PE GUI 4.0
entry start

include '%fasminc%\win32a.inc'
include '%fasminc%\Riched32.inc'
section '.code' code readable executable

  start:
        invoke  LoadLibrary, RichEditDllName
        invoke  GetModuleHandle,0
        mov     [wc.hInstance],eax
        invoke  RegisterClass, wc
        invoke  CreateWindowEx,0,myClass,myTitle,WS_VISIBLE+WS_OVERLAPPEDWINDOW,CW_USEDEFAULT, CW_USEDEFAULT, 700, 400, NULL, NULL, [wc.hInstance],NULL
        mov     [hWndMain], eax
        invoke  InitCommonControls
        invoke  GetCurrentProcess
        mov     [hProcess], eax
  msg_loop:
        invoke  GetMessage,msg,NULL,0,0
        or      eax,eax
        jz      end_loop
        invoke  TranslateAccelerator, [hWndMain], [hAccel], msg
        or      eax, eax
        jnz     msg_loop
        invoke  IsDialogMessage, [hWndMain], msg
        or      eax, eax
        jnz     msg_loop
        invoke  TranslateMessage,msg
        invoke  DispatchMessage,msg
        jmp     msg_loop
  end_loop:
        invoke  ExitProcess,[msg.wParam]

proc wndProc hwnd,wmsg,wparam,lparam
        push    ebx esi edi
        cmp     [wmsg],WM_DESTROY
        je      .wmDESTROY
        cmp     [wmsg],WM_CREATE
        je      .wmCREATE
        cmp     [wmsg], WM_NOTIFY
        je      .wmNOTIFY
    .wmDEFAULT:
        invoke  DefWindowProc,[hwnd],[wmsg],[wparam],[lparam]
        jmp     .wmBYE
    .wmNOTIFY:
        mov     eax, [lparam]
        cmp     [eax+MSGFILTER.msg], WM_LBUTTONDOWN
        je      .wmNwmLBD
        jmp     .wmDEFAULT

;**************  PROBLEM AREA **********************

    .wmNwmLBD:
        int3            ; the four alternatives I've tried.
        invoke  SendMessage, [editHnd], EM_CHARFROMPOS, 0, [eax+MSGFILTER.lparam]
;        invoke  SendMessage, [hWndMain], EM_CHARFROMPOS, 0, [eax+MSGFILTER.lparam]
;        invoke  SendMessage, [editHnd], reEM_CHARFROMPOS, 0, [eax+MSGFILTER.lparam]
;        invoke  SendMessage, [hWndMain], reEM_CHARFROMPOS, 0, [eax+MSGFILTER.lparam]

;***************************************************

        shr     eax, 16         ;0 based line No. should now be in eax
        stdcall Word2Asc, eax, tmpBuff
        invoke  SetWindowText, [hWndMain], tmpBuff
        jmp     .wmDEFAULT
    .wmCREATE:
        invoke  GetClientRect, [hwnd], rect
        invoke  CreateWindowEx, WS_EX_CLIENTEDGE, RichEditClass, NULL, WS_CHILD+WS_VISIBLE+WS_VSCROLL+WS_HSCROLL+ES_AUTOVSCROLL+ES_AUTOHSCROLL+ES_MULTILINE+ES_WANTRETURN, [rect.left], [rect.top], [rect.right], [rect.bottom], [hwnd], NULL, [wc.hInstance], NULL
        mov     [editHnd], eax
        invoke  SendMessage,[editHnd],EM_SETEVENTMASK,0,ENM_MOUSEEVENTS ;capture mouse events in edit control
        invoke  SetWindowText, [editHnd], tmpStr
        jmp     .wmBYE
    .wmDESTROY:
        invoke  PostQuitMessage,0
        xor     eax,eax
    .wmBYE:
        pop     edi esi ebx
        ret
endp

proc Word2Asc HexVal, buff
        push    eax ebx ecx edx edi
        mov     eax, [HexVal]
        mov     ebx, 0x0A
        mov     ecx, 5
    @@:
        xor     edx, edx
        div     ebx
        add     edx, 0x30
        push    edx
        loop    @b
        mov     edi, [buff]
        mov     ecx, 5
    @@:
        pop     eax
        stosb
        loop    @b
        pop     edi edx ecx ebx eax
        ret
endp


section '.data' data readable writeable

reEM_CHARFROMPOS        = WM_USER+39
tmpBuff                 db 5 dup 'X', 0
editHnd                 dd ?
hWndMain                dd ?
hProcess                dd ?
hAccel                  dd ?
msg                     MSG
rect                    RECT
wc                      WNDCLASS 0, wndProc, 0, 0, NULL, NULL, NULL, COLOR_BTNFACE+1, NULL, myClass
RichEditDllName         db 'riched20.DLL', 0
RichEditClass           db 'RICHEDIT20A', 0
myTitle                 db 'Test', 0
myClass                 db 'Test', 0
ENM_MOUSEEVENTS         = 0x00020000
tmpStr                  db 'A line of text in the window', 0x0D, 0x0A
                        db 'A line of text in the window', 0x0D, 0x0A
                        db 'A line of text in the window', 0x0D, 0x0A
                        db 'A line of text in the window', 0x0D, 0x0A
                        db 'A line of text in the window', 0x0D, 0x0A
                        db 'A line of text in the window', 0x0D, 0x0A
                        db 'A line of text in the window', 0x0D, 0x0A
                        db 'A line of text in the window', 0x0D, 0x0A
                        db 'A line of text in the window', 0x0D, 0x0A
                        db 'A line of text in the window', 0x0D, 0x0A
                        db 'A line of text in the window', 0x0D, 0x0A, 0
struct  MSGFILTER
        nmhdr           NMHDR
        msg             dd ?
        wparam          dd ?
        lparam          dd ?
ends


section '.idata' import data readable writeable

library kernel32,'KERNEL32.DLL',\
        user32,  'USER32.DLL',\
        gdi32,   'GDI32.DLL',\
        comdlg32,'COMDLG32.DLL',\
        advapi32,'ADVAPI32.DLL',\
        comctl32,'COMCTL32.DLL'

include '%fasminc%\apia\Kernel32.inc'
include '%fasminc%\apia\User32.inc'
include '%fasminc%\apia\Gdi32.inc'
include '%fasminc%\apia\Comdlg32.inc'
include '%fasminc%\apia\Advapi32.inc'
include '%fasminc%\apia\Comctl32.inc'
    

The return value specifies the character index in the low-order word and the line index in the high-order word

.
.
invoke  SendMessage, [editHnd], EM_CHARFROMPOS, 0, pt
invoke  SendMessage, [editHnd], EM_LINEFROMCHAR, eax, 0
.
.