Sources: release notes 3.19.0, breaking changes, CHANGELOG.md
For some time now (years), Flutter has had two key event systems implemented. The new system reached parity with the old platform-specific raw key event system, and the raw system has been deprecated.
`ScrollBehavior`s now allow or disallow scrolling speeds to be affected by the number of pointers on the screen. `ScrollBehavior.multitouchDragStrategy`, by default, prevents multiple pointers interacting with the scrollable at the same time from affecting the speed of scrolling.
During accessibility focus traversal, `Tooltip.message` is visited immediately after `Tooltip.child`.
Flutter apps included an asset file named `AssetManifest.json`. This file effectively contains a list of assets. Application code can read it using the `AssetBundle` API to determine what assets are available at runtime.
In accordance with Flutter's Deprecation Policy, deprecated APIs that reached end of life after the 3.16 stable release have been removed.
To build a Flutter app for Android, Flutter's Gradle plugins must be applied. Historically, this was done imperatively with Gradle's legacy, imperative apply script method.