Private Declare Function EnableWindow Lib "user32.dll" ( _
   ByVal hwnd As Long, _
   ByVal fEnable 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 GetDesktopWindow Lib "user32.dll" () As Long
 
Private Declare Function SetActiveWindow Lib "user32.dll" ( _
   ByVal hwnd As Long) As Long
 
 
Private Const GWL_HWNDPARENT = -8
 
' diese Zeile steht im normalerweise im Modul
' und die Variable wird in Sub Main ermittelt und gesetzt
Public OwnerHwnd As Long
 
Private Sub Form_Load()
 
  ' neuen Besitzer festlegen
  SetWindowLong Me.hwnd, GWL_HWNDPARENT, OwnerHwnd
 
  ' Fokus auf Desktop setzen (entfernt die aktiven Fenstertitelzeile)
  SetActiveWindow GetDesktopWindow
 
  ' neuen Besitzer disablen
  EnableWindow OwnerHwnd, 0
 
  ' Fokus auf Childfenster setzen
  SetActiveWindow Me.hwnd
End Sub
 
Private Sub Form_Unload(Cancel As Integer)
 
  ' den erzwungenen Besitzer wieder enablen
  EnableWindow OwnerHwnd, 1
 
End Sub

Viel Spass,
R@lf