<Button Name="btn11" Padding = "5" 
        Click="ChangePadding" TabIndex="1">
  Padding
</Button>

Private Sub ChangePadding(ByVal Sender As Object, ByVal e As RoutedEventArgs)

    If (btn11.Padding.Left = 5.0) Then
        btn11.Padding = New Thickness(2.0)
        btn11.Content = "Control Padding changes from 5 to 2."
    Else
        btn11.Padding = New Thickness(5.0)
        btn11.Content = "Padding"
    End If

End Sub