Features I would like to see in FXML

I really enjoy using FXML, it is robust, simple and well supported by the Scene Builder tool but there are some features I would really like to see.

Controllers allowed on arbitrary nodes

Large controls usually have many action methods, many controls injected with the @FXML annotation and typically other objects like DAOs which can get quite messy.  Sometimes handling code for a single control such as a combo box can get quite large, creating an FXML for a small control seems like overkill.

To tackle this, it would be useful to allow the fx:controller attribute on any FXML element specifying a node that is loaded into the scene graph.  This 'sub-controller' would have controls injected with @FXML annotations in the same way as root controller except that the it would not be able have it's parent controls injected.  Only the element it is declared on or that element's children could be injected.

Allow effects to be created in Scene Builder and then injected into a controller

It is much easier to create effects in Scene Builder than it is in Java code because I can get instant feedback and fine tune much easier.  It would be great if I could create an effect in FXML and have it injected into the controller using an @FXML annotation.

Support 'Actions'

One of the things that I miss from Swing is the javax.swing.Action interface.  This was used to encapsulate action logic of a button in a single class instead of having many action listeners in one class.  I could create a class implementing EventHandler and set it on the button in the controller class, but it would be nice to specify it under the code tab in the same as you would specify a method to handle an event.

Specify some validations on TextField controls

For Me, FXML is all about productivity so it makes sense that it could support common requirements such as validations on TextField controls.  For example, a TextField might only allow numeric input up to a maximum number.  If you google "javafx numeric textfield" there are already many varied implementations.  It would be great to see this in Scene Builder, even better if it could be tested in preview mode.