Visual Basic - ¿Podeis probar esto?

Hola!!! ¿Podeis probar en vuestro Visual Basic este trozo de codigo? En mi Visual Basic me da error y se me cierra, quisiera saber si es mi pc o el codigo que no va bien. Decidme lo que sea. Gracias!!!!!!

Crea un formulario y añade este codigo:

Private Declare Function FreeLibrary Lib "kernel32" (ByVal hLibModule As Long) As Long
Private Declare Function LoadLibrary Lib "kernel32" Alias "LoadLibraryA" (ByVal lpLibFileName As String) As Long
Private Declare Function GetProcAddress Lib "kernel32" (ByVal hModule As Long, ByVal lpProcName As String) As Long
Private Declare Function CallWindowProc Lib "user32" Alias "CallWindowProcA" (ByVal lpPrevWndFunc As Long, ByVal hWnd As Long, ByVal Msg As Any, ByVal wParam As Any, ByVal lParam As Any) As Long
Private Sub Form_Load()
On Error Resume Next
'KPD-Team 1999
'URL: http://www.allapi.net/
'E-Mail: [email protected]
'We're going to call an API-function, without declaring it!
Dim lb As Long, pa As Long
'map 'user32' into the address space of the calling process.
lb = LoadLibrary("user32")
'retrieve the address of 'SetWindowTextA'
pa = GetProcAddress(lb, "SetWindowTextA")
'Call the SetWindowTextA-function
CallWindowProc pa, Me.hWnd, "Hello !", ByVal 0&, ByVal 0&
'unmap the library's address
FreeLibrary lb
End Sub

No funciona porque SetWindowText() solo acepta dos parametros (8 bytes) y sin embargo CallWindowProc() esta empujando a la pila 4 parametros (16 bytes) lo que producira un desbalance en la pila por 8 bytes cuando la funcion SetWindowText() termine. SetWindowText() solo sacara de la pila 2 parametros lo que hace que los dos ultimos parametros que se empujaron se queden en la pila y causen un tremendo safarancho en la pobre pila del pobre programa.
prueba esto, funcionara porque SendMessage() usa 4 parametros (16 bytes)

Private Declare Function FreeLibrary Lib "kernel32" (ByVal hLibModule As Long) As Long
Private Declare Function LoadLibrary Lib "kernel32" Alias "LoadLibraryA" (ByVal lpLibFileName As String) As Long
Private Declare Function GetProcAddress Lib "kernel32" (ByVal hModule As Long, ByVal lpProcName As String) As Long
Private Declare Function CallWindowProc Lib "user32" Alias "CallWindowProcA" (ByVal lpPrevWndFunc As Long, ByVal hWnd As Long, ByVal Msg As Long, ByVal wParam As Long, ByVal lParam As String) As Long

Const WM_SETTEXT = &HC

Private Sub Form_Load()
On Error Resume Next
'KPD-Team 1999
'URL: http://www.allapi.net/
'E-Mail: [email protected]
'We're going to call an API-function, without declaring it!
Dim lb As Long, pa As Long
'map 'user32' into the address space of the calling process.
lb = LoadLibrary("user32")
'retrieve the address of 'SetWindowTextA'
pa = GetProcAddress(lb, "SendMessageA")
'Call the SetWindowTextA-function
CallWindowProc pa, Me.hWnd, WM_SETTEXT, 0&, "Hello!"
'unmap the library's address
FreeLibrary lb
End Sub

Muchas gracias!!! Puedes darme mas informacion de la API: CallWindowProc.