message: Use 10% black on hover / 20% black on press for Start/Stop button (win)
diff: <Setter TargetName="StartButton" Property="Visibility" Value="Collapsed" />
  </Trigger>
  <Trigger Property="IsMouseOver" Value="True">
  - <Setter TargetName="OverlayEllipse" Property="Fill" Value="#0D000000" />
  + <Setter TargetName="OverlayEllipse" Property="Fill">
  + <Setter.Value>
  + <SolidColorBrush Color="Black" Opacity="0.1" />
  + </Setter.Value>
  + </Setter>
  </Trigger>
  <Trigger Property="IsPressed" Value="True">
  - <Setter TargetName="OverlayEllipse" Property="Fill" Value="#19000000" />
  + <Setter TargetName="OverlayEllipse" Property="Fill">
  + <Setter.Value>
  + <SolidColorBrush Color="Black" Opacity="0.2" />
  + </Setter.Value>
  + </Setter>
  </Trigger>
  </ControlTemplate.Triggers>
  </ControlTemplate>
  