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 SendMessage Lib "user32" Alias _
      "SendMessageA" (ByVal hWnd As Long, ByVal wMsg As Long, _
      ByVal wParam As Integer, ByVal lParam 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 GWL_EXSTYLE As Long = (-20)
Private Const WS_EX_DLGMODALFRAME As Long = &H1
Private Const WM_SETICON = &H80

Private hWndForm As Long
Private bIcon As Boolean

Private Sub UserForm_Initialize()
  imgIcon.Visible = False

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

  bIcon = True
  ChangeIcon
  SetUserFormStyle
End Sub

Private Sub SetUserFormStyle()
  Dim frmStyle As Long

  If hWndForm = 0 Then Exit Sub

  frmStyle = GetWindowLong(hWndForm, GWL_EXSTYLE)

  If bIcon Then
    frmStyle = frmStyle And Not WS_EX_DLGMODALFRAME
  Else
    frmStyle = frmStyle Or WS_EX_DLGMODALFRAME
  End If

  SetWindowLong hWndForm, GWL_EXSTYLE, frmStyle

  DrawMenuBar hWndForm
End Sub

Private Sub ChangeIcon()
  Dim hIcon As Long

  On Error Resume Next
  If hWndForm <> 0 Then
    If bIcon Then
      hIcon = imgIcon.Picture
    Else
      hIcon = 0
    End If
    SendMessage hWndForm, WM_SETICON, True, hIcon
    SendMessage hWndForm, WM_SETICON, False, hIcon
  End If
End Sub

Private Sub optIconOn_Click()
  bIcon = True
  ChangeIcon
  SetUserFormStyle
End Sub

Private Sub optIconOff_Click()
  bIcon = False
  ChangeIcon
  SetUserFormStyle
End Sub