Description

This PR updates the NestedScrollCoordinator to prioritize scrolling 'away' any inner overscroll before any of the outer/inner positions. Previously, if you did not lift your finger from the screen and allow the overscroll to bounce back, the overscroll would stick and scroll in between the inner and outer scrollables.

Bug behavior:

Fixed behavior:

Related Issues

#29264
#17518

Tests

I updated the nested overscroll related tests. This is not being considered a breaking change. Although existing tests needed to be changed, there was a TODO stating these expectations when this was fixed. The comments around these tests were acknowledging that the expected behavior was bad. Ran through internal tests and everything passed, customer tests are passing as well. :)

Checklist

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• I read the Contributor Guide and followed the process outlined there for submitting PRs.
• I signed the CLA.
• I read and followed the Flutter Style Guide, including Features we expect every widget to implement.
• I read the Tree Hygiene wiki page, which explains my responsibilities.
• I updated/added relevant documentation (doc comments with ///).
• All existing and new tests are passing.
• The analyzer (flutter analyze --flutter-repo) does not report any problems on my PR.
• I am willing to follow-up on review comments in a timely manner.

Breaking Change

Did any tests fail when you ran them? Please read Handling breaking changes.

• No, this is not a breaking change.