Shouldn't rays go behind the control panel?

[zepumph]

From #154

[zepumph]

Even with all this important stuff, I still feel like it should be behind:

[veillette]

For reference, the issue of z-layers was also raised in #112.
Assigning to @arouinfar.

[kathy-phet]

@arouinfar and @kathy-phet decided to revisit the constraints of the lens to make its up down motion less.

[pixelzoom]

I was asked to evaluate this for https://github.com/phetsims/geometric-optics/milestone/1. But in the previous comment, I see that design decisions have not been made, so there's nothing I can do.

[pixelzoom]

Also worth noting:

• It's not just the rays that go in front of the control panel. Many other things are in front of the control panel. The virtual image, the lens, the mirror, ...

• The things that are in front of the control panel are BEHIND the controls at the top of the screen (combo box, etc.)

[pixelzoom]

9/23/21 design meeting: Move play area behind everything else. Closing.