Option Explicit
 
' benötigte API-Deklarationen
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 Const GWL_STYLE = (-16)
Private Const WS_CAPTION = &HC00000
Dim nStyle As Long
 
' Fensterstil ändern
Private Sub Command1_Click()
 
With Form1
  ' aktuellen Fensterstil emitteln
  nStyle = GetWindowLong(.hwnd, GWL_STYLE)
 
  ' Titelleiste entfernen
  'nStyle = nStyle And Not WS_CAPTION
 
  ' Neuen Fensterstil setzen
  SetWindowLong .hwnd, GWL_STYLE, (nStyle And Not WS_CAPTION)
End With
 
End Sub
 
Private Sub Command2_Click()
With Form1
  ' aktuellen Fensterstil emitteln
  'nStyle = GetWindowLong(.hwnd, GWL_STYLE)
 
  ' Titelleiste entfernen
  'nStyle = nStyle And WS_CAPTION
 
  ' Neuen Fensterstil setzen
  SetWindowLong .hwnd, GWL_STYLE, nStyle
 
  .Visible = False
  .Visible = True
End With
 
 
End Sub