fix: UAP buttons misplaced when drawer opens via keyboard

[Who-is-PS]

Description

UAP buttons appeared in wrong position when opening drawer via keyboard navigation. Position was calculated during CSS transition before it settled.

Changed to continuous position monitoring while buttons are visible, matching the existing PortalOverlay pattern.

Related links, issue #, if available: AWSUI-61721

How has this been tested?

Review checklist

The following items are to be evaluated by the author(s) and the reviewer(s).

Correctness

• Changes include appropriate documentation updates.
• Changes are backward-compatible if not indicated, see CONTRIBUTING.md.
• Changes do not include unsupported browser features, see CONTRIBUTING.md.
• Changes were manually tested for accessibility, see accessibility guidelines.

Security

• If the code handles URLs: all URLs are validated through the checkSafeUrl function.

Testing

• Changes are covered with new/existing unit tests?
• Changes are covered with new/existing integration tests?

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.19%. Comparing base (8eeade2) to head (588c5ea).
⚠️ Report is 7 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4238   +/-   ##
=======================================
  Coverage   97.19%   97.19%           
=======================================
  Files         886      886           
  Lines       26008    26030   +22     
  Branches     9421     9435   +14     
=======================================
+ Hits        25278    25300   +22     
+ Misses        724      683   -41     
- Partials        6       47   +41     

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[georgylobko]

Does this code ever run? It's in the same function scope, so once the useEffect cleans up, this variable is already out of scope

[jperals]

My understanding is that since checkPosition is called with requestAnimationFrame, there is a non-zero chance that the component unmounted in-between —that is what cleanedUp tracks.

[Who-is-PS]

The cleanedUp variable is captured by closure in both the checkPosition function and the cleanup function. When cleanup runs and sets cleanedUp = true, the pending rAF callback still has access to it via closure and will see the updated value, causing it to exit.

[pan-kot]

why do we introduce cleanedUp flag instead of cancelling the requested animation frames?

[Who-is-PS]

Valid point, I will update it with cancelAnimationFrame. It is cleaner

[pan-kot]

I see that a mock for requestAnimationFrame is added - but where is the test to ensure that the position is recomputed on every animation frame?

[jperals]

Nit: could these be consts?

[Who-is-PS]

Refactored it to const.

[jperals]

Why assign to a snapshot instead of just calling the callbacks first and clearing rafCallbacks afterwards?

[Who-is-PS]

Because callbacks re-register themselves (animation loop). If we clear after executing, the newly registered callback is lost.

[jperals]

I see that a mock for requestAnimationFrame is added - but where is the test to ensure that the position is recomputed on every animation frame?

I see that a unit test for this has now been added, I'm OK with it but think that visual regression test is better here —testing the actual result and not depending so much on implementation details.