CustomMenu: background color for header?

I've observed a difference in how CustomMenu and Menu2 render on the Epix Pro 2. In the simulator, both menu types display a black background. However, on the actual device, Menu2 has a greyish background, similar to the native Garmin menus. In contrast, the CustomMenu header remains fully black on the real watch.

I'm trying to make the CustomMenu header match the native look. I attempted to use :backgroundColor, but that seems to only affect the header text background, not the entire header area.

One workaround would be to override drawHeader(), draw a grey rectangle manually, and then draw the header drawable on top.

But is there a cleaner way to set the full header background color for CustomMenu?