Как запретить юзеру жать на "Х" окна?

Private Declare Function GetSystemMenu Lib 'User32' (ByVal hWnd As Integer, ByVal bRevert As Integer) As Integer
Private Declare Function RemoveMenu Lib 'User32' (ByVal hMenu As Integer, ByVal nPosition As Integer, ByVal wFlags As Integer) As Integer
Const MF_BYPOSITION = &H400
 
Private Sub MDIForm_Load()
    RemoveMenu GetSystemMenu(hWnd, 0), 6, MF_BYPOSITION ''Disable Close
    RemoveMenu GetSystemMenu(hWnd, 0), 4, MF_BYPOSITION ''Disable Maximize
    RemoveMenu GetSystemMenu(hWnd, 0), 3, MF_BYPOSITION ''Disable Minimize
End Sub

''Можно так (у меня это работает)
 
Private Declare Function DeleteMenu Lib 'user32' (ByVal hMenu As Long, ByVal nPosition As Long, ByVal wFlags As Long) As Long
Private Declare Function GetSystemMenu Lib 'user32' (ByVal hwnd As Long, ByVal bRevert As Long) As Long
 
Private Const MF_BYPOSITION = &H400&
 
Private ReadyToClose As Boolean
Private Sub RemoveMenus(frm As Form, _
remove_restore As Boolean, _
remove_move As Boolean, _
remove_size As Boolean, _
remove_minimize As Boolean, _
remove_maximize As Boolean, _
remove_seperator As Boolean, _
remove_close As Boolean)
Dim hMenu As Long
 
'' Get the form''s system menu handle.
hMenu = GetSystemMenu(hwnd, False)
 
If remove_close Then DeleteMenu hMenu, 6, MF_BYPOSITION
If remove_seperator Then DeleteMenu hMenu, 5, MF_BYPOSITION
If remove_maximize Then DeleteMenu hMenu, 4, MF_BYPOSITION
If remove_minimize Then DeleteMenu hMenu, 3, MF_BYPOSITION
If remove_size Then DeleteMenu hMenu, 2, MF_BYPOSITION
If remove_move Then DeleteMenu hMenu, 1, MF_BYPOSITION
If remove_restore Then DeleteMenu hMenu, 0, MF_BYPOSITION
End Sub
 
Private Sub cmdClose_Click()
ReadyToClose = True
Unload Me
End Sub
 
Private Sub Form_Load()
'' Remove the Close system menu item and the
'' menu separator.
RemoveMenus Me, False, False, _
False, False, False, True, True
End Sub
 
'' Cancel if ReadyToClose is false.
Private Sub Form_QueryUnload(Cancel As Integer, UnloadMode As Integer)
Cancel = Not ReadyToClose
End Sub

Declare Function GetSystemMenu Lib 'user32' (ByVal hwnd As Long, ByVal bRevert As Long) As Long
 
Declare Function GetMenuItemCount Lib 'user32' (ByVal hMenu As Long) As Long
 
Declare Function DrawMenuBar Lib 'user32' (ByVal hwnd As Long) As Long
 
Declare Function RemoveMenu Lib 'user32' (ByVal hMenu As Long, ByVal nPosition As Long, ByVal wFlags As Long) As Long
 
Public Const MF_BYPOSITION = &H400&
Public Const MF_REMOVE = &H1000&
 
Private Sub Form_Load()
 
Dim hSysMenu As Long
Dim nCnt As Long
 
'' Show the form
Me.Show
 
'' Get handle to our form''s system menu (Restore, Maximize, Move, close etc.)
hSysMenu = GetSystemMenu(Me.hwnd, False)
 
If hSysMenu Then
'' Get System menu''s menu count
nCnt = GetMenuItemCount(hSysMenu)
If nCnt Then
'' Menu count is based on 0 (0, 1, 2, 3...)
RemoveMenu hSysMenu, nCnt - 1, MF_BYPOSITION Or MF_REMOVE
RemoveMenu hSysMenu, nCnt - 2, MF_BYPOSITION Or MF_REMOVE 
'' Remove the seperator
DrawMenuBar Me.hwnd 
'' Force caption bar''s refresh. Disabling X button
Me.Caption = 'Try to close me!'
End If
End If
 
End Sub

Dim f as boolean
 
Private Sub btExit_Click()
  f = True
  Unload Me
End Sub
 
Private Sub Form_Unload(Cancel As Integer)
  If Not f Then Cancel = True
End Sub

Option Explicit
Private Declare Function GetSystemMenu Lib 'user32' Alias _
        'GetSystemMenu' (ByVal hwnd As Long, ByVal bRevert As Long) _
        As Long
Private Declare Function RemoveMenu Lib 'user32' Alias 'RemoveMenu' _
        (ByVal hMenu As Long, ByVal nPosition As Long, _
        ByVal wFlags As Long) As Long
Private Const MF_BYPOSITION = &H400&
 
Public Sub RemoveCloseMenu(frm As Form)
    Dim hSysMenu As Long
    ' Get the system menu for the form
    hSysMenu = GetSystemMenu(frm.hwnd, 0)
    ' Remove the close item
    Call RemoveMenu(hSysMenu, 6, MF_BYPOSITION)
    ' and the seperator
    Call RemoveMenu(hSysMenu, 5, MF_BYPOSITION)
End Sub

   RemoveCloseMenu Me

FormName_QueryUnload(....)
Cancel = True
...