Review inputEnabledProperty

[pixelzoom]

https://github.com/phetsims/scenery/issues/1158 changed pickableProperty to inputEnabledProperty. Review this sim's use of inputEnbledProperty. Locate candidates by searching for addInputListener.

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These sim-specific candidates are candidates for inputEnabledProperty:

• naturalSelection.introScreen.view.environmentNode - This is the top panel that shows the environment and bunnies hopping around. Pressing anywhere other than on a bunny clears the Pedigree graph.
• naturalSelection.introScreen.view.environmentNode.sprites - This is the scenery Sprites for the bunnies shown in the environment view. If a press here lands on a bunny, that bunny is selected in the Pedigree graph.
• naturalSelection.introScreen.view.graphs.populationNode.populationGraphNode.dataProbeNode - This is the data probe in the Population graph. All parts of it are draggable, and it has a sphere at the bottom to encourage dragging.

@amanda-phet @kathy-phet questions:

1. Do you want to instrument any of these elements?
2. Does the look of any of these elements need to change when inputEnabledProperty is false? (For example, do we need to hide the sphere at the bottom of the data probe?)

[kathy-phet]

I would favor adding it to this node: naturalSelection.introScreen.view.environmentNode.sprites - so that if you decide to remove the pedigree chart option, you can also turn off the bunny selection entirely.

The other two I would not add it to at this point as I cannot think of a condition you would want this behavior. If a client has a reason to want it that we cannot think of right now, then we can add it later.

[pixelzoom]

Sounds good to me. @amanda-phet do you agree?

[amanda-phet]

Yes that sounds good.

I was starting to write a case for instrumenting naturalSelection.introScreen.view.environmentNode but I changed my mind in the process. I also don't think it's useful to make the data probe not pickable.

[pixelzoom]

*.view.environmentNode.sprites.inputEnabledProperty has been instrumented. If there is a selected bunny, the selection is cleared when inputEnabledProperty is set to false.

@amanda-phet please review in master.

[amanda-phet]

Looks like it is working just fine.