I have experienced a little bug with Fox.
Using inner view, When some smoke is in front of me, i can see it, but the little window, (over the steering wheel) i cant.

Not a big problem, but better to report

Yes, the same happens with rubber marks. Probably a minor error in the rendering order of alpha-blended textures. It's already known and should be somewhere on Scawen's bugfix list

The same thing happens in the Shift+U Mode.
If you add an object it isnt visible behind the buttons.
But I think, it such an minor thing. Don't worry about it. ;-)