Option Explicit

Private Declare Function FindWindow Lib "user32" Alias _
      "FindWindowA" (ByVal lpClassName As String, ByVal _
      lpWindowName As String) As Long

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

Private Declare Function DrawMenuBar Lib "user32" (ByVal _
      hwnd As Long) As Long

Private Const SC_CLOSE As Long = &HF060

Private hWndForm As Long
Private bCloseBtn As Boolean

Private Sub UserForm_Initialize()
  If Val(Application.Version) >= 9 Then
    hWndForm = FindWindow("ThunderDFrame", Me.Caption)
  Else
    hWndForm = FindWindow("ThunderXFrame", Me.Caption)
  End If

  bCloseBtn = False
  SetUserFormStyle
End Sub

Private Sub SetUserFormStyle()
  Dim frmStyle As Long
  Dim hSysMenu As Long

  If hWndForm = 0 Then Exit Sub

  If bCloseBtn Then
    hSysMenu = GetSystemMenu(hWndForm, 1)
  Else
    hSysMenu = GetSystemMenu(hWndForm, 0)
    DeleteMenu hSysMenu, SC_CLOSE, 0&
  End If

  DrawMenuBar hWndForm
End Sub

Private Sub optCloseOn_Click()
  bCloseBtn = True
  cmdBeenden.Cancel = True
  SetUserFormStyle
End Sub

Private Sub optCloseOff_Click()
  bCloseBtn = False
  cmdBeenden.Cancel = False
  SetUserFormStyle
End Sub