Llamar procedimiento por dirección

[[EX3]]

No se usa solo para subclasificar ventanas, un ejemplo:

Código:

Option Explicit

 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

    Dim lb As Long, pa As Long

    'Cargamos la libreria user32.dll en memoria:
    lb = LoadLibrary("user32")

    'Obtenemos la direccion de la funcion MessageBoxA():
    pa = GetProcAddress(lb, "MessageBoxA")

    'Realizamos una llamada a la funcion MessageBoxA():
    Call CallWindowProc(pa, Me.hWnd, "Hola mundo desde el API de Windows!", "Prueba de CallWindowProc", MB_ICONEXCLAMATION)

    'Descargamos la libreria de la memoria:
    Call FreeLibrary(lb)

 End Sub 

Salu2...