SplitViewNavigator ignores backgroundAlpha value

The SplitViewNavigator component ignores the backgroundAlpha value. I'm certain of this because I set the backgroundAlpha="0" and the backgroundColor="0xFF0000" and tested it and saw a big red screen.

I copied the SplitViewNavigatorSkin code into my own skin and set the backgroundAlpha to 0 by changing line 132 -> graphics.beginFill(color, 0);