Pane tabs: Scroll entire new tab into view (#36827)

The state of the child bounds is not up-to-date when `scroll_to_item`
gets triggered, causing the new tab to not scroll completely into view.

Closes #36317 

Release Notes:

- Fix an issue where a new tab is only partially visible on creation.
49335d54behrou0003 committed on 9/30/2025, 9:04:34 AM· committed by GitHubparent624e448
3 files changedLine totals unavailable