[2.6.0+] Passage editors do not retain scroll state

[hituro]

Describe the bug.

When opening more than one passage editor at a time, inactive editors (those not on top of the stack) do not retain their scroll state.

Steps to reproduce:

Create a passage long enough to scroll. Scroll it. Open a second editor. When you return the first, scroll has been lost.

Expected behavior:

Scroll state should be retained

Additional context on this problem.

No response

Twine version number

2.6.0+

Does this problem occur with the web version of Twine or the desktop app?

Desktop app

What operating system does this problem occur on?

Other

If this problem is occurring with the web version of Twine, what browser does it occur on?

Firefox

Presubmission checklist

• I am interested in working on code that would fix this bug. (This is not required to submit a bug report.)
• I have done a search and believe that an issue does not already exist for this bug in the GitHub repository.
• If this problem is occurring with the app version of Twine, it still happens after I remove the user.css file from my Twine folder. (You would've added this file yourself. If you don't understand this question, you can safely check this box.)
• I have read and agree to abide by this project's Code of Conduct.

[klembot]

The reason why this happens is that for performance, Twine doesn't render the code editor area unless it's visible. So we'd need to add some mechanism for remembering this when the editor goes to the background.