Every now and then I have encountered the need to traverse and inspect the JavaFX scene graph. In one recent example, my task was to selectively adorn UI controls with other controls for enhanced accessibility. Other people have also tried to do similar things, as indicated by some StackOverflow questions and blog posts [0].
The JavaFX scene graph consists of user-created nodes, as well as nodes that are created by control skins. While APIs like `Parent.getChildrenUnmodifiable` can be used to traverse the scene graph, this only works once it is connected to a scene and skins have been applied. The scene graph can also change quite dramatically depending on particular control skins, and generally does not correspond to the "logical graph" that was defined in FXML or in code. Adding an API like `Parent.getLogicalChildrenUnmodifiable` would solve that issue quite easily, and it would also enable the inspection of subgraphs that are not connected to a scene. The logical graph could be used to inspect the document structure of the code, independent of the applied control skins. For example, `Button.getLogicalChildrenUnmodifiable` would return a single node, namely the value of the ´graphic` property (or no node, if there is no graphic). `ScrollPane.getLogicalChildrenUnmodifiable` would return the value of the `content` property, and so on. The downside is, of course, that the responsibility of defining logical nodes would need to be imposed on third-party controls. It stands to reason that such a feature might need to be an opt-in feature in order to prevent breaking changes. However, even if only implemented in the core controls that ship with JavaFX, it might still be a useful addition for many applications. [0] http://www.kware.net/?p=8
