Should screen follow balloon when zoomed in and using keyboard nav

[KatieWoe]

Test device
Dell
Operating System
Win 11
Browser
Chrome
Problem description
For phetsims/qa#721.
When zoomed in, if you drag a balloon to the edge of the screen with a mouse the screen will pan to follow it. However, if you drag it with keyboard nav the balloon will go off screen and the screen will not pan to follow it. You will continue to manipulate the balloon as if it were still visible and hear sounds to go with it.
Steps to reproduce

1. Zoom the screen in and pan it to one side of the screen
2. Use keyboard nav to pick up a balloon and move it around the screen

Visuals

Troubleshooting information:

!!!!! DO NOT EDIT !!!!!
Name: ‪Balloons and Static Electricity‬
URL: https://phet-dev.colorado.edu/html/balloons-and-static-electricity/1.5.0-rc.2/phet/balloons-and-static-electricity_all_phet.html?showPointerAreas
Version: 1.5.0-rc.2 2021-10-11 21:55:48 UTC
Features missing: applicationcache, applicationcache, touch
Flags: pixelRatioScaling
User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/95.0.4638.54 Safari/537.36
Language: en-US
Window: 1280x649
Pixel Ratio: 1.5/1
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: 4096
Texture: size: 16384 imageUnits: 16 (vertex: 16, combined: 32)
Max viewport: 32767x32767
OES_texture_float: true
Dependencies JSON: {}

[jessegreenberg]

This was actually recently fixed in master and a very small change so I brought it into the balloons-and-static-electricity 1.5 branch.

[Nancy-Salpepi]

@jessegreenberg should the screen pan when keyboard shortcuts such as j+w are used? As of now, the screen won't pan until the balloon is moved after such shortcuts are used. I just wanted to make sure this was expected behavior.

[Nancy-Salpepi]

@jessegreenberg
In addition, when zoomed in a little and moving the balloon, the panning isn't smooth across the bottom and middle of screen.

[Nancy-Salpepi]

Sorry @jessegreenberg, I have one last question about this
Should the screen pan to follow the balloon once it is released?

[jbphet]

My vote would be no. Following a thing that has been consciously selected by the user makes sense. Following something that the user does not have selected seems to me like it would open a big can of worms for the UI design. How would we decide what to follow and what not to if multiple things were moving? I think we should keep it simple, and follow things that have focus, but no other movement.

[Nancy-Salpepi]

@jbphet - any thoughts on #550 (comment) and #550 (comment) ?

[jbphet]

@jbphet - any thoughts on #550 (comment) and #550 (comment) ?

@jessegreenberg will need to respond to those questions.

[jbphet]

I'm making an executive decision that the questions just above are not blocking for the 1.5 release. I'll remove the ready-for-qa label and let @jessegreenberg take it from here, and any additional fixes can go on master.