Only show edit hint on components from the tool box

[phet-steele]

Currently, in each Black Box challenge with a component in Reveal, the screen displays a "Tap circuit element to edit." hint. This is true for all challenges except challenge Black Box 2, which doesn't display a hint since Reveal only contains a wire. This could be a dead giveaway to some students; after I showed @arouinfar this, she proposed that the "Tap circuit element to edit." hint only appears/applies to components dragged from the tool box. This would effectively change each challenge to never display the hint without a user dropping their own component in the play area. The hint would go away when all user-placed components are removed.

Seen on Win 10 & OSX 10.11.5 Chrome. For phetsims/tasks#643.

[arouinfar]

@samreid can you address this before we deliver a new version to Stanford? I wouldn't be surprised if a few students figure out this unintentional hint.

[samreid]

Fixed above and ready for review in next version.

[samreid]

Testable version in #197

[phet-steele]

Looks good in 1.0.0-dev.22

[arouinfar]

Actually, something's not quite right here...

• In Investigate, drag editable component into play area, and the edit hint appears (as it should).
• Switch to Build, the edit hint remains, despite there being no editable components that are clickable. (I think the edit hint should disappear here.)
• Drag wire into box, edit hint disappears. (Edit hint should have disappeared as soon as switching to Build, since there weren't any editable components inside the box.)
• Switch back to Investigate, edit hint should be visible, but is not.

[phet-steele]

Thanks @arouinfar!

[samreid]

In the preceding commit, the hint updates when the mode changes, and it seems to have the correct behavior for the scenario @arouinfar described above. Note that the hint does not appear for wires because they cannot be edited (though they can be deleted). Ready for review in next version.

[samreid]

The test issue is #203

[samreid]

@arouinfar can you please test this in the version linked above?

[arouinfar]

Looks good!