Jak přidat tlačítko minimize na FixedWindow

Pokud potřebujete na Fixed okno vložit tlačítko minimalizovat, musíte oknu zaslat zprávu API funkcí SetWindowLong. Jak na to, demonstruje náš kód.
Příklad:

Option Explicit

'Deklarace API
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

'Konstanty pro styl okna
Private Const GWL_STYLE = (-16)
Private Const WS_MINIMIZEBOX = &H20000
Private Const WS_MAXIMIZEBOX = &H10000

Private Function AddMinimizeButton(po_Form As Form)
   Dim ll_Style As Long
   ll_Style = GetWindowLong(po_Form.hwnd, GWL_STYLE)
   Call SetWindowLong(po_Form.hwnd, GWL_STYLE, ll_Style Or _
   WS_MINIMIZEBOX)
End Function

Private Sub Form_Load()
    AddMinimizeButton Me
End Sub