Con este código puedes deshabilitar todos los botones, incluso puedes evitar que tu formulario puedan cambiarlo de tamaño.
Option Explicit
Private Declare Function GetSystemMenu Lib "user32" (ByVal hwnd As Long, ByVal bRevert As Long) As Long
Private Declare Function DeleteMenu Lib "user32" (ByVal hMenu As Long, ByVal nPosition As Long, ByVal wFlags As Long) As Long
'Constantes
Const SC_SIZE = &HF000
Const SC_MOVE = &HF010
Const SC_MINIMIZE = &HF020
Const SC_MAXIMIZE = &HF030
Const SC_CLOSE = &HF060
Const SC_RESTORE = &HF120
Const MF_SEPARATOR = &H800
Const MF_BYPOSITION = &H400
Const MF_BYCOMMAND = &H0
Private Sub MDIForm_Load()
Dim hwnd&, hMenu&, Success&
Dim i%
hwnd = Me.hwnd
hMenu = GetSystemMenu(hwnd, 0)
'Quitar todos (va de 0 a 8)
For i = 8 To 0 Step -1
Success = DeleteMenu(hMenu, i, MF_BYPOSITION)
Next
Exit Sub
'Usa esto para quitar los menús que te interesen:
Success = DeleteMenu(hMenu, SC_SIZE, MF_BYCOMMAND)
Success = DeleteMenu(hMenu, SC_MOVE, MF_BYCOMMAND)
Success = DeleteMenu(hMenu, SC_CLOSE, MF_BYCOMMAND)
'Success = DeleteMenu(hMenu, SC_MINIMIZE, MF_BYCOMMAND)
'Success = DeleteMenu(hMenu, SC_MAXIMIZE, MF_BYCOMMAND)
'Success = DeleteMenu(hMenu, SC_RESTORE, MF_BYCOMMAND)
End Sub
Espero que te sirva de ayuda.
Saludos,
Roberto García
