Private Function FindWindowFromHandle(ByVal hWnd As IntPtr) As Control
      If hWnd = Me.Handle Then Return Me
      For Each c As Control In Controls
         If hWnd = c.Handle Then Return c
 
         If c.Controls.Count > 0 Then Return FindWindowFromHandle(c.Handle)
      Next
 
      Return Nothing
   End Function
 
   Public Function PreFilterMessage(ByRef m As System.Windows.Forms.Message) _
     As Boolean Implements System.Windows.Forms.IMessageFilter.PreFilterMessage
 
      Select Case m.Msg
         Case WM_MOUSEMOVE
            If Not mouseInClient Then
               controlWithMouse = FindWindowFromHandle(m.HWnd)
               If controlWithMouse IsNot Nothing Then
                  Timer1.Enabled = True
                  mouseInClient = True
               End If
            End If
 
         Case WM_MOUSELEAVE
            mouseInClient = False
            If controlWithMouse IsNot Nothing Then
               Timer1.Enabled = True
               controlWithMouse = Nothing
            End If
      End Select
 
      Return False
   End Function
 
   Private fullShown As Boolean
   Private fullHidden As Boolean
   Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As _
     System.EventArgs) Handles Timer1.Tick
      If mouseInClient Then
         If fullShown Then Exit Sub
         Debug.WriteLine("Form anzeigen")
         fullShown = True
         fullHidden = False
      Else
         If fullHidden Then Exit Sub
         Debug.WriteLine("Form verstecken")
         fullShown = False
         fullHidden = True
      End If
 
      Timer1.Enabled = False
   End Sub