Private Sub Timer1_Timer()
    Dim C As Control
 
    For Each C In Me.Controls
        If TypeOf C Is TextBox Or TypeOf C Is ComboBox Then
            If C = Me.ActiveControl And C.Index = Me.ActiveControl.Index Then
                C.BackColor = vbYellow
            Else
                C.BackColor = vbWhite
            End If
        End If
    Next
End Sub

mfg
brave@heart

...bis zur unendlichkeit und noch viel weiter...