The JavaFX collections framework offers the `FXCollections.concat(ObservableList...)` method, which creates a new modifiable list that contains a concatenated snapshot of the source lists, backed by an `ArrayList`. However, when the source lists are changed, the concatenated list is not updated.
This PR adds `FXCollections.concatenatedObservableList(ObservableList...)`, which creates an _unmodifiable collection view_ onto the source lists that represents the concatenation of all source elements. When any of the source lists are changed, the change is also reflected in the concatenated view. ------------- Commit messages: - Added concatenated observable list Changes: https://git.openjdk.org/jfx/pull/1087/files Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=1087&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8305925 Stats: 459 lines in 3 files changed: 448 ins; 3 del; 8 mod Patch: https://git.openjdk.org/jfx/pull/1087.diff Fetch: git fetch https://git.openjdk.org/jfx.git pull/1087/head:pull/1087 PR: https://git.openjdk.org/jfx/pull/1087
