Incorrect background colors when switching between challenges

[phet-steele]

@samreid, we nailed two different procedures to have the sim show an incorrect background color (@andrea-phet and I):

1. After sim load, go to Black Box screen
2. Start on a black box challenge of your choosing
3. Enter Build mode
4. Switch to a different challenge
5. Switch back to your original challenge in step 2

You will still be in Build mode on your original challenge, but the background outside of the black box will not be the "pale" blue, just the normal blue.

1. After sim load, go to Black Box screen
2. Start on a black box challenge of your choosing
3. Switch to a different challenge
4. Enter Build mode
5. Switch back to your original challenge in step 2

We've just switched steps 3 & 4, but now you will be on your original challenge in Investigate mode with the "pale" blue background.

Seen on Win 7 & 10 Chrome. For phetsims/tasks#643.
Troubleshooting information:
Name: ‪Circuit Construction Kit: Black Box Study‬
URL: http://www.colorado.edu/physics/phet/dev/html/circuit-construction-kit-black-box-study/1.0.0-dev.19/circuit-construction-kit-black-box-study_en.html
Version: 1.0.0-dev.19 2016-07-12 22:00:54 UTC
Flags: pixelRatioScaling
User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/51.0.2704.106 Safari/537.36
Language: en-US
Window: 1536x739
Pixel Ratio: 2.5/1
WebGL: WebGL 1.0 (OpenGL ES 2.0 Chromium)
GLSL: WebGL GLSL ES 1.0 (OpenGL ES GLSL ES 1.0 Chromium)
Vendor: WebKit (WebKit WebGL)
Vertex: attribs: 16 varying: 30 uniform: 1024
Texture: size: 16384 imageUnits: 16 (vertex: 16, combined: 32)
Max viewport: 16384x16384
OES_texture_float: true
Dependencies JSON: {"assert":{"sha":"7d27130a","branch":"master"},"axon":{"sha":"9a0e2f3a","branch":"master"},"babel":{"sha":"5b1f70f3","branch":"master"},"brand":{"sha":"f0b1f7da","branch":"master"},"chipper":{"sha":"8825397d","branch":"master"},"circuit-construction-kit-black-box-study":{"sha":"0496b8ff","branch":"master"},"circuit-construction-kit-common":{"sha":"9c38befc","branch":"master"},"dot":{"sha":"3628c3ae","branch":"master"},"joist":{"sha":"94bc734c","branch":"master"},"kite":{"sha":"88f0c3a0","branch":"master"},"phet-core":{"sha":"c48bf320","branch":"master"},"phetcommon":{"sha":"35ef94ad","branch":"master"},"scenery":{"sha":"942889ad","branch":"master"},"scenery-phet":{"sha":"0d6b589e","branch":"master"},"sherpa":{"sha":"03590a07","branch":"master"},"sun":{"sha":"b4a2dc38","branch":"master"},"tandem":{"sha":"a8ac284b","branch":"master"}}

[samreid]

Fixed above, ready for review in next version.

[samreid]

The test issue is #203

[samreid]

@phet-steele can you please test whether this is resolved in the version linked above?

[phet-steele]

Looks resolved @samreid.