JEP 253: Prepare JavaFX UI Controls & CSS APIs for Modularization

Jonathan Giles jonathan.giles at
Tue May 19 08:50:24 UTC 2015

It's late and I'm writing this on my phone, but briefly, I think you've missed the 'project two' section: input maps are how behaviors are now specified, as a collection of inputs that map to some event handling code.

All skins do in this environment is install a series of these mappings into the control input map. These are all accessible as public API.

The big thing you miss out on is actually having access to the code within these event handlers (wish are all gathered in the behavior class). But you can always replace an input mapping with new code.

I can clarify more tomorrow if things are unclear or if you have any further questions.

-- Jonathan
Sent from a touch device. Please excuse my brevity.

On 19 May 2015 20:39:28 GMT+12:00, Robert Zenz <robert.zenz at> wrote:
>> The intention is to move many JavaFX control skins into the
>> public package, most probably There is no
>> intention to also move the related behavior classes, since these will
>> be handled separately as part of Project Two below.
>> ...
>> Project Two: Improve support for input mapping
>There is a need to have access to the behaviors as well, not only the
>The skins and behaviors are very tightly coupled, extending a control
>extending the behavior is possible but is not intended according to the
>it also allows to easily fix bugs which might be encountered.
>Before I give some examples, I'd like to tell you our exact usecase.
>We provide an Enterprise Application Framework called JVx, the good
>thing about
>is that it provides a "write once, run anywhere" approach by providing
>a basic
>UI toolkit that can be ported to all kinds of technologies (Swing,
>Vaadin and
>JavaFX being the currently supported ones). This means that we have a
>fixed set
>of features that every GUI toolkit that we port to should be able to
>So you can imagine it as four layers:
>1. Our UI toolkit classes.
>2. Implementations of the needed interfaces.
>3. Extensions of the GUI toolkit.
>4. The GUI toolkit itself (f.e. JavaFX or Swing).
>This approach allows us to transparently fix bugs and add missing
>of the GUI toolkit in the extension layer, without the client or user
>while working with JVx.
>Enough of that, some examples:
>* RT-40149, TabPane does misbehave if the last tab is disabled. This
>was only
>   possible to fix easily at the behavior level. Not having access to
> the behavior would in this case mean that we would need to fix that at
>the control level...which means a lot of code for intercepting keys and
>   re-wiring behavior.
>* Additionally we added the possibility to deactivate the Ctrl+Tab
>combo on
>   the TabPane, which was very easily and cleanly done in the behavior.
>* RT-40623/RT-40269, change the values of a Spinner with up/down keys
>   the mousewheel. Adding this features was done in the behavior.
>I'm sure that the JFXtras and efxclipse projects have very similar
>regarding access to the behaviors.
>There is an additional "problem" in there, most skins have the
>dependency on their behavior counterpart. This makes it nearly
>to only extend the behavior part of the control. Currently we need to
>to reflection to change the behavior of the skin at runtime to achieve
>which is, as you can imagine, a solution I'd like to get rid of
>Example, you want to change something in the TabPaneBehavior.
>The control creates the TabPaneSkin with createDefaultSkin(), the skin
>instantiates the TabPaneBehavior in its constructor. You can extend the
>and override createDefaultSkin() to create your own skin. But if you
>now want
>to use an extension of the TabPaneBehavior, you have to resort to
>1. Not calling the skin constructor is not an option, as there is a lot
>of setup done there, but it instantiates the behavior it wants
>2. Writing your own skin from scratch is possible, but a lot of
>    work.
>3. Copy the sourcecode of the skin and behavior and fix it in your
>    which is something to stay away from because it creates unnecessary
>duplication. Also you need to update the copied code with the new
>with every JDK release. Then there's also the license question and so
>4. Filing a bug/feature request is the correct way of action, however
>for it to be done (including waiting for a new JDK release/update)
>    not be viable.
>A decoupling of the skin and behaviors (for example by providing an
>constructor that does accept the behavior) would further ease the
>of extending already existing controls.
>If I might have misunderstood something about this JEP, or how
>the control/skin/behavior works, please feel free to correct me.

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