Once I have more than one area of the UI (e.g., adding config, live
video, or a scrub bar prototype), I'll use this for a pull-down menu to
go between them, and maybe add a filter icon to do what this does. But
this works for now and most closely matches the old UI.
I tried to use a Collapse or Slide transition, but I had trouble getting
it to work on both desktop and mobile. In particular, the way I used the
flex wrap to display the selectors on the left/above doesn't seem
compatible with picking an orientation. If I pick the wrong orientation,
the list views won't fill the empty space.