Support for alternative input

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@kathy-phet asked me to add alternative input to ph-scale and ph-scale-basics.

This includes:

• add "supportsInteractiveDescription": true to package.json
• keyboard traversal order
• KeyboardDragListener for pH probe in the Macro screen
• KeyboardDragListener for water faucets in Macro and Micro screens - common code, see Alternative input design for FaucetNode scenery-phet#773
• KeyboardDragListener for dropper in Macro and Micro screens
• PressListener for momentary button on dropper - common code, see Alt input is broken for momentary buttons. sun#796
• KeyboardDragListener for interactive graph indicators in the MySolution screen
• hot keys?
• keyboard help dialogs

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@kathy-phet @arouinfar FYI...

After discussion with @arouinfar, here's the list of things that are not going to be straightforward:

• Momentary button on dropper
• Dragging the dropper while the momentary button is pressed
• Faucet interaction and keyboard help, because it's common code (will require design)
• Which draggable things should have their own keyboard help, vs something like "Move Draggable Items" (MoveDraggableItemsKeyboardHelpSection) that appears in Geometric Optics?

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After consulting with @arouinfar, no hot keys are necessary.

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Alt input for ph-scale is currently blocked by 2 issues:

• Alternative input design for FaucetNode scenery-phet#773
• Alt input is broken for momentary buttons. sun#796

That said, it's at a point where it's ready for @arouinfar to review.

I took my best guess at traveral order and keyboard help.

KeyboardDragListeners (for the draggable things) are configured like this:

• eye dropper: dragVelocity: 300, shiftDragVelocity: 20
• pH probe: dragVelocity: 300, shiftDragVelocity: 20
• graph indicators: dragVelocity: 300, shiftDragVelocity: 40 (the indicator will not move with smaller values, due to precision of the model value)

Let me know what you'd like to change. And assign this issue back to me. Thanks!

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In #249 (comment), @arouinfar said:

Let’s just turn it off completely, then.

Alternative input was disabled in the above commits, by removing "supportsInteractiveDescription": true from package.json for ph-scale and ph-scale-basics.

Unassigning and labeling this issue as deferred, to be addressed sometime after publication of 1.6 PhET-iO.

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In the above commits, I also commented out createKeyboardHelpNode in all Screens. Otherwise the keyboard help is created and disposed by the State wrapper, and we'll have the memory leak. These lines of code (noted with a TODO referencing this issue) should be restored when work on this is resumed.

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In 2d1e8b0, @jonathanolson added "supportsInteractiveDescription": true to package.json for the Description prototype. This turns on alt input, which is still not completely supported. So labeling this issue as blocks-sim-publication.

As for the status of alt input...

• FaucetNode support for alt input was added in Alternative input design for FaucetNode scenery-phet#773 and Keyboard help content for FaucetNode scenery-phet#839.
• Momentary buttons still do not support alt input, and this sim uses RoundMomentaryButton specifically.

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420ac61 by @jonathanolson will need to be reviewed when work on alternative input resumes. That change prevents setting the pdomOrder when running with ?supportsDescriptionPlugin.

[jonathanolson]

Noted in discussions that the description logic plugin will control the pdomOrder when the query parameter is true.

Additionally, committed above to put the DescriptionRegistry change above under the query parameter, so that our sim actions are 100% query parameter feature-flag controlled.

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In Slack#description-tooling, there was a request to add alt input support for FaucetNode. That support has been available for a long time. The issue is that alt input is "off" for ph-scale and ph-scale-basics. So...

As a result of the above commits, alt input is now "on" by default for ph-scale and ph-scale-basics. I checked FaucetNode, and it’s working as expected. Both sims also have the “Faucet Controls” section in their keyboard help.