api로 mdi 창에서 최대.최소화 버튼 없애보자

[code vb]
Option Explicit
 
Private Const GWL_STYLE = (-16)
Private Const WS_MAXIMIZEBOX = &H10000
Private Const WS_MINIMIZEBOX = &H20000
Private Const WS_SYSMENU = &H80000
Private Declare Function GetWindowLong Lib "user32" Alias "GetWindowLongA" (ByVal hWnd As Long, ByVal nIndex As Long) As Long
Private Declare Function SetWindowLong Lib "user32" Alias "SetWindowLongA" (ByVal hWnd As Long, ByVal nIndex As Long, ByVal dwNewLong As Long) As Long
Private Declare Function GetSystemMenu Lib "user32" (ByVal hWnd As Long, ByVal bRevert As Long) As Long
 
 
Private Const SC_MAXIMIZE = &HF030&
Private Const SC_MINIMIZE = &HF020&
Private Const SC_SIZE = &HF000&
Private Const MF_BYCOMMAND = &H0&
Private Declare Function DeleteMenu Lib "user32" (ByVal HMenu As Long, ByVal nPosition As Long, ByVal wFlags As Long) As Long
Private Declare Function DrawMenuBar Lib "user32" (ByVal hWnd As Long) As Long
 
 
Private Sub MDIForm_Load()
 
    Dim rtnLong As Long
    Dim HMenu As Long
    rtnLong = GetWindowLong(Me.hWnd, GWL_STYLE)
    rtnLong = rtnLong And Not WS_MAXIMIZEBOX
    rtnLong = rtnLong And Not WS_MINIMIZEBOX
    rtnLong = rtnLong And Not WS_SYSMENU           '아이콘도 사라집니다'
    SetWindowLong Me.hWnd, GWL_STYLE, rtnLong
  
    HMenu = GetSystemMenu(Me.hWnd, 0)
    DeleteMenu HMenu, SC_MAXIMIZE, MF_BYCOMMAND
    DeleteMenu HMenu, SC_MINIMIZE, MF_BYCOMMAND
    DeleteMenu HMenu, SC_SIZE, MF_BYCOMMAND
 
    DrawMenuBar Me.hWnd
End Sub
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