Option Explicit

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

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 DrawMenuBar Lib "user32" (ByVal _
      hwnd As Long) As Long

Private Const GWL_STYLE As Long = -16
Private Const WS_SYSMENU As Long = &H80000

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

  If hWndForm = 0 Then Exit Sub

  frmStyle = GetWindowLong(hWndForm, GWL_STYLE)

  If bCloseBtn Then
    frmStyle = frmStyle Or WS_SYSMENU
  Else
    frmStyle = frmStyle And Not WS_SYSMENU
  End If

  SetWindowLong hWndForm, GWL_STYLE, frmStyle

  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