...
                        else if (appTaskbar.Position == TaskbarPosition.Left)
                        {
                            left = appTaskbar.Size.Width;
                            w.MaxHeight = SystemParameters.MaximizedPrimaryScreenHeight;
                            w.MaxWidth = SystemParameters.MaximumWindowTrackWidth - appTaskbar.Size.Width;
                        }
...
                        w.WindowState = WindowState.Maximized;