Private Sub Timer1_Timer()
     Dim C  As Control
     Dim HasFocus as Integer
     For Each C In Me.Controls
          HasFocus = Me.ActiveControl.hWnd
          If TypeOf C Is TextBox  Then
             If C.hWnd = HasFocus Then
                    C.BackColor = vbYellow
               Else
                    C.BackColor = vbWhite
               End If
          End If
     Next
End Sub

Uli

Wissen ist Macht; nichts wissen macht auch nichts!