Public Class Form1
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
Private Declare Function DrawMenuBar Lib "User32" (ByVal hwnd As Integer) As Integer
Private Declare Function GetMenuItemCount Lib "User32" (ByVal hMenu As Integer) As Integer
Private Const MF_BYPOSITION = &H400&
Private Const MF_DISABLED = &H2&
Private Sub disableX(ByVal wnd As Form)
Dim hMenu As Integer, nCount As Integer
hMenu = GetSystemMenu(wnd.Handle.ToInt32, 0)
nCount = GetMenuItemCount(hMenu)
Call RemoveMenu(hMenu, nCount - 1, MF_BYPOSITION Or MF_DISABLED)
DrawMenuBar(Me.Handle.ToInt32)
End Sub
Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
disableX(Me)
End Sub