Private Const GWL_STYLE As Long = (-16&)
Private Const WS_THICKFRAME As Long = &H40000
Private Const WS_MINIMIZEBOX As Long = &H20000
Private Const WS_MAXIMIZEBOX As Long = &H10000
Private Const SWP_NOSIZE = &H1
Private Const SWP_NOMOVE = &H2
Private Const SWP_NOZORDER = &H4
Private Const SWP_FRAMECHANGED = &H20
Private Declare Function GetWindowLong Lib "user32" Alias "GetWindowLongA" ( _
  ByVal hWnd&, ByVal nIndex&) As Long
Private Declare Function SetWindowLong Lib "user32" Alias "SetWindowLongA" ( _
ByVal hWnd&, ByVal nIndex&, ByVal dwNewLong&) As Long
Private Declare Function SetWindowPos Lib "user32" (ByVal hWnd&, ByVal _
hWndInsertAfter&, ByVal x&, ByVal y&, ByVal cx&, ByVal cy&, ByVal wFlags&) As _
Long
 
 
Private Sub Command1_Click()
    Call SetWindowLong(hWnd, GWL_STYLE, GetWindowLong(hWnd, GWL_STYLE) Xor ( _
      WS_THICKFRAME Or WS_MINIMIZEBOX Or WS_MAXIMIZEBOX))
    Call SetWindowPos(hWnd, 0&, 0&, 0&, 0&, 0&, SWP_NOMOVE Or SWP_NOSIZE Or _
    SWP_NOZORDER Or SWP_FRAMECHANGED)
End Sub