solid interactive highlight can appear when moving 2 balls with multitouch

[Nancy-Salpepi]

Test device
iPad 9th generation

Operating System
iPadOS 17.6.1

Browser
Safari

Problem description
For phetsims/qa#1134, on the Balance Point screen with interactive highlights enabled, it is possible to make the highlight a solid square instead of a dashed one while moving two balls at the same time and lifting your fingers every once in a while. It was easiest to reproduce when the balls were on top of one another, but that is not a requirement for it to happen.
@KatieWoe is also able to reproduce

Steps to reproduce
It is difficult to have exact steps

1. Turn on interactive highlights
2. Move two balls at once, releasing every once in a while so that which ball has the focus changes.

Visuals
Here are 2 videos but the screen recording doesn't show touches so it is hard (impossible) to tell exactly what I did.

solidSquare2.mov

squaresolid.mov

[Nancy-Salpepi]

@KatieWoe please add any other thoughts you have on steps to reproduce.

[KatieWoe]

I'd seen this when slightly zoomed in if I slide a finger over the ball instead of directly grab it. From the videos above this does not seem necessary to the bug.

[jbphet]

I am unable to duplicate this on my Dell Windows laptop with touchscreen after about 5 minutes of testing. This seems like a low severity bug that doesn't interfere with the use of the sim in any significant way. @marlitas and I are thinking that this should not block the release of the sim and we should just ignore it. If it seems to get worse (easier to reproduce or having more severe impact on the sim), we'd be happy to do more investigation. Closing.