Dear John:

Now with the test sprint over, let me try to respond to your earlier questions 
(sorry for the delay!).

> What is the point of TraversalEvent.NODE_TRAVERSED?
My understanding it's an alternative to adding a 
TraversalEngine.TraverseListener in the original implementation.
The main purpose, I think, is to notify the control of the fact that its child 
got focus.
You might be right that it might be possible to replace the event by adding a 
listener to Scene.focusOwnerProperty, though it's likely to complicate the 
event handling machinery in the skins.

> What does it mean if I filter this event? What if I consume it?
Current behavior of Skins that depend on it will break.

Were there other questions?  Please let me know.


Allow me to summarize various suggestions and ideas floated during the 
discussion:

Additional problems:

  *   existing problem of consuming events that had no effect on the control(s)
  *   priority of handling e.g. accelerators vs regular key events

You proposed an alternative design which consists of

  *   creating a new hierarchy of TraversalEvents
  *   separate KeyEvents and TraversalEvents (Directional and Logical).
  *   redesigning controls and Scene to react to these instead of KeyEvents
  *   add 2 properties to Parent (Directional and Logical)
  *   TraversalPolicy enum { OPEN, CONFINED, CYCLIC, IGNORED }

The benefits of this idea are:

  *   ability to completely customize traversal ("crazy custom navigation")
  *   setting of traversal policies with CSS

Some additional issues were touched upon during the discussion:

  *   ScrollPane consuming navigational keys

  *   some (ScrollPane, Spinner, TextField)  control needlessly consume key 
events (see also JDK-8320557)

  *   possible accessibility regression with ScrollPane


Is this a complete list?  Did I miss anything?

-andy




From: John Hendrikx <john.hendr...@gmail.com>
Date: Thursday, September 19, 2024 at 07:24
To: Andy Goryachev <andy.goryac...@oracle.com>, openjfx-dev@openjdk.org 
<openjfx-dev@openjdk.org>
Subject: Re: [External] : Re: Proposal: Focus Traversal API

My apologies then, I was a bit impatient.  Good luck with the test sprint then!

--John
On 18/09/2024 17:13, Andy Goryachev wrote:
Oh, sorry, I did not mean to ignore your comments.  I should have mentioned we 
are having a bi-annual "test sprint" and work exclusively on the test suite.  
You made a lot of good comments that require some thought and careful 
consideration, for which I simply had no spare CPU cycles last week or this 
week.  Sorry, will definitely respond in detail early next week.

-andy


From: John Hendrikx <john.hendr...@gmail.com><mailto:john.hendr...@gmail.com>
Date: Tuesday, September 17, 2024 at 23:05
To: Andy Goryachev 
<andy.goryac...@oracle.com><mailto:andy.goryac...@oracle.com>, 
openjfx-dev@openjdk.org<mailto:openjfx-dev@openjdk.org> 
<openjfx-dev@openjdk.org><mailto:openjfx-dev@openjdk.org>
Subject: Re: [External] : Re: Proposal: Focus Traversal API

Andy,

As you're not responding to any of the suggestions or any of my questions, but 
are only re-iterating points that I believe are not going to be a benefit to 
the long term viability of FX, I see no point in continuing the discussion 
further.

--John
On 18/09/2024 01:09, Andy Goryachev wrote:
Dear John:

You do bring a lot of good points, no doubt.  And I do agree with a lot of the 
suggestion, but I still want to emphasize two points:

1. The backward compatibility should not be dismissed that easily.  There is a 
number of existing applications out there and we do not want to break them.  
Whether the behavior is specified or not is irrelevant, we do not want to cause 
mayhem from the customers and developers alike whose keyboard navigation 
suddenly changed.

2. I question the cost benefit analysis of the redesign idea.  While I agree 
with you that it might help with some unusual cases, the overall benefit is 
rather limited.  The benefit of the proposed solution is, in my opinion, far 
greater: it allows for custom traversal policies (a feature that has been 
requested multiple times) and enables focus traversal from custom components, 
something of a lesser value, but still important.  Exposing the existing APIs 
is a relatively cheap solution that will give us two features at nearly zero 
cost.  On the other hand, I doubt that our team, or yourself, are willing 
commit substantial development effort to redesign the thing to use events.  
Which brings me to the choice I mentioned earlier: realistically, we have a 
choice of providing two requested features soon, or never.

I would also encourage other members of the development community to voice 
their opinion on the subject, perhaps there is something else we can do to move 
forward.

Thank you
-andy


From: John Hendrikx <john.hendr...@gmail.com><mailto:john.hendr...@gmail.com>
Date: Saturday, September 14, 2024 at 09:41
To: Andy Goryachev 
<andy.goryac...@oracle.com><mailto:andy.goryac...@oracle.com>, 
openjfx-dev@openjdk.org<mailto:openjfx-dev@openjdk.org> 
<openjfx-dev@openjdk.org><mailto:openjfx-dev@openjdk.org>
Subject: [External] : Re: Proposal: Focus Traversal API

Hi Andy,

First let me say that when it comes to designing an API, you really need to 
take the time to think the solution through.  The current internal solution was 
probably kept internal for exactly that reason, insufficient time to work out 
the kinks and look into alternatives.

An API is almost impossible to change later, so the general rule is that if 
you're not sure about an API, then its better to have no API.  This is why I 
think it is important that we first look for what the API should look like, 
then worry about how this can be fitted onto JavaFX.  Making concessions 
related to the current implementation before having a clear idea of how the API 
should preferably work is not part of that.  You start making concessions only 
when it turns out the preferred design would encounter unresolvable problems in 
the current implementation.

Since I think there is very little public API related to focus traversal, nor 
is there any specification of how it currently works, I think we have a lot of 
room to maneuver.  This is why I think we should first reach a consensus on the 
API, then look how it can be fitted on top of FX.  Sometimes a well thought out 
API also is a natural fit, and may be easier to migrate to than you think.
On 14/09/2024 00:17, Andy Goryachev wrote:
Dear John, Everyone:

Thank you for a thoughtful response!  Some of the ideas you described 
definitely deserve further consideration.  If I were to summarize:

1. move the focus traversal logic away from the components and into the Scene
2. re-implement focus traversal through TraversalEvents rather than responding 
directly to KeyEvents
3. (more) standard policies
4. using CSS

(there is of course more topics in your response, but let me start with the 4 
above)

#1

I generally like this idea.  In some sense it is already how things work 
internally, but without the ability to customize that (i.e. by introducing 
custom traversal keys, or removing existing ones).  The downside is 
substantial: not only we'd need to re-design the whole of the focus traversal, 
but also rework the existing control's behaviors.  Did I mention the risk of 
regression, given the absence of comprehensive behavioral tests?

There's two things here.

1. There is no need to re-design the whole focus traversal.  The old internal 
system can be gradually replaced (it works by directly consuming KeyEvents 
after all).

2. Regression.  When nothing is specified, and the fact that controls **ought** 
to work like other common controls in different UI toolkits, is it a regression 
when focus traversal works the same as those other platforms, even if it may be 
a regression from the point of view of FX?  For example, a Spinner will 
currently react to any mouse key, where as other common toolkits only react to 
the left mouse button.  Is it a regression if FX is adjusted to also only react 
to the left mouse button?  It's not specified anywhere.

I think we have sufficient space to maneuver here as long as we are not making 
focus traversal completely different from how it commonly works in UI's.
Can there be regressions versus the current (unspecified) implementation?  
Sure, there can be.  Is that necessarily bad?  That depends.  If the new focus 
traversal works like it does on all other toolkits, then no, it is more of a 
bug fix.  Did we break something with the new implementation?  That's always 
possible, but will then be fixed as soon as it is reported.

#2

This may or may not be an integral part of #1.  Potentially, it allows for 
injection of events by the application code, as well as simplifies creation of 
complex custom controls.  The latter becomes possible with the original 
proposal, so net benefit is limited to the first part, I think.
I think TraversalEvents are quite central to making this an API that will 
really stand the test of time.  It leverages the existing event system, giving 
you all the power that comes with it.  You did not answer my question about the 
TraversalEvents in your design.  Why are the Events when they can't be 
triggered, filtered or consumed?

#3

One obvious possibility is to enable creation of a simple policy based on a 
list of Nodes.  I must mention one use case that is impossible to cover with 
pre-defined policy is one where navigation depends on some state.  Such a 
policy must be implemented programmatically.  I think one property should be 
sufficient - I am strongly against adding two properties here.

Programmatic escapes can always be achieved by responding directly to a 
TraversalEvent.  I think however this should be a rare case, and standard 
policies should really cover almost all use cases.  It may be a gap that should 
be investigated, and the API adjusted for (usually the "exceptions" are well 
worth looking into to see if with a tweak they can't become "standard").  As 
for being "strongly against" having two properties -- that's an odd stance to 
take without motivating it.  It could also be rolled into "one" where the 
Policy is a record with the two values, but I think we're getting ahead of 
ourselves here.  First the API, then the implementation.

I do think however there is great value in having the Logical and Directional 
navigation split.  Often you'll only want to replace one of these with a custom 
policy (or a different standard policy), so that the other navigation method 
can be used to escape the control.  For example, a Toolbar could be tabbed in 
an out of (using Logical navigation) while the Directional navigation is cyclic 
(and thus can't be used to escape the control's context).

#4

The idea of using CSS to specify traversal policy seems wrong to me: the CSS 
defines the presentation aspects (styles) rather than behavioral ones.  I know 
it is possible to set custom skins and the corresponding behavior via CSS, and 
we know why (skins define the appearance), but we should not go beyond that, in 
my opinion.

I see no problem styling such properties.  They're FX properties, and it would 
be very convenient to style them to globally alter how focus works, instead of 
having to rely on, say, Builders or Factories for controls where traversal 
policies can be applied.  There are also already properties that don't only 
influence the look of controls.  "-fx-skin" being the most obvious one, but 
there is also "-fx-focus-traversable", "-fx-context-menu-enabled", 
"-fx-block-increment", "-fx-unit-increment", "-fx-pannable", 
"-fx-initial-delay", "-fx-repeat-delay", "-fx-collapsible", "-fx-show-delay", 
"-fx-show-duration", "-fx-hide-delay", and probably more.  Aside from 
"-fx-skin" none of these properties have a visual impact, but instead alter 
behavior.

Note: I'm not saying this needs to be there immediately.  I just want to make 
sure we're not closing off this direction, as again, it would be a huge hassle 
to do this programmatically.  In "code" the only things I usually do on my 
controls are the following:

- I define the container hierarchy (VBox, HBox, which children go where)
- I set a style name
- I set anything that unfortunately cannot be CSS styled (things like ALWAYS, 
SOMETIMES, NEVER grow policies, Grid sizes, etc, things that are clearly 
"visual" but still can't be styled).

All the rest I don't touch, or want to touch.  Having to select a traversal 
policy for every control of type X I create is just cumbersome and unnecessary. 
 There will be a call then to set this "globally", and then there will be the 
question, do we make something custom with many limitations because it doesn't 
fit our conceptions of what (FX) CSS is for (ie, not style, but only *visual* 
style) or do we just expose these properties as Styleable leveraging an 
existing powerful system with almost zero effort?
--

There is one more aspect of the problem that I think we should consider.  The 
current proposal does not change the implementation in any material way, nor 
does it change the behavior, thus can be done quickly.  The benefit everyone 
gets from it is ability to trigger focus traversal and to control it via custom 
policies.  Any other solution will require resources and the bandwidth we 
currently don't have, which means the probability of it being added to FX is 
virtually zero.  Let me emphasize, I am not against attempting to discuss or 
implement the best possible solution, but we should be aware of the limitations 
of the reality we live in.

"Quickly" and API's are incompatible with each other.  There is nothing worse 
than exposing an API quickly, which then becomes a burden on the system -- I 
think the current CSS API is a prime example of where "quickly" has gone wrong, 
costing us tremendous amounts of effort to make even minor changes to it.

I urge you to ignore the current implementation, think thoroughly how (in an 
ideal world) you would want such an API to work (from a user perspective, not 
from an implementor's perspective) and only then see how this could be made to 
fit into JavaFX.

This is exactly what I did.  I did not look at the implementation, although I'm 
aware of some of it.  I looked at how I as a user of FX am building 
applications, the struggles I have with it currently, (with controls for 
example "eating" KeyEvents), and how I would like to be able to adjust focus 
traversal.  Do I want to respond to "KeyCode.LEFT" or do I want to respond to 
"TraversalEvent.LEFT"?  Do I also need to respond to "KeyCode.NUM_PAD_LEFT"?  
These things should be abstracted, and preferably I should just be able to 
choose from common navigation standards.  And when I do want to change such a 
standard, in 99% of the cases that will be the case for all similar controls in 
my application.  How do I do such things currently if I want to change 
something for all controls in my application?  I use CSS.

Also I think this can be implemented gradually.  Here's a potential plan:

1. Have Scene listen to unused KeyEvents and translate them to TraversalEvents

Benefit: gives custom controls a way to respond to keyboard based navigation in 
a platform agnostic way; this probably already removes the biggest roadblock 
for custom controls...

Public API: Limited to a new Event

2. Start converting existing controls to listen to TraversalEvent instead of 
KeyEvent

This hits a lot of controls, but should be relatively easy to do, and it can be 
all kept internal for now.  It can be done in a few batches.

Benefit: for each control converted, user can now programmatically trigger 
focus changes, and by overriding things at Scene level can completely change 
navigation keys

Public API: none

3. Implement a number of standard policies internally (OPEN, CONFINED, CYCLIC, 
IGNORED)

Convert any controls that could use these as their default, removing any custom 
logic if it happens to match one of the defaults.

Benefit: less code to maintain and debug, gives us experience with which 
policies make sense and where the gaps are

Public API: none

Order: It is possible to do this before 2, and so some of the control 
conversions could just consist of removing their custom logic, and selecting a 
standard policy.

4. Expose policy property/properties on Parent

Any controls that are not using a custom policy anymore (of type IGNORED) can 
now be user adjusted.  We don't have to guarantee that each policy makes sense 
for each control. Changing a default IGNORED policy to a standard one will 
change the behavior (as intended) but it need not be a "complete" behavior that 
users like.  This is not FX's problem, and can be improved upon later.

Benefit: users can now change policies on any existing control, even ones with 
a custom policy; many of the controls may support a switch between OPEN, 
CONFINED and CYCLIC out of the box.
Public API: new properties on Parent

5. Perhaps expose some helpful tools to calculate the "next" Node for a given 
traversal option.

This can be done at any stage, and can be considered completely separate.  It 
is IMHO a relatively low priority need.

Benefit: less work for control implementors (although they could just "copy" 
said code)

Public API: Maybe some methods in Node, or some kind of static helper.

6. CSS styleable properties

If we really want to give power to our users, and impress them with a flexible 
focus traversal API, then make these properties styleable.

Benefit: allow users to pick any control, and set is policy globally or within 
a subset of controls (ie. dialogs, popups, etc).

Public API: Nothing in Java, but document as CSS properties

--John

Thank you,
-andy




From: openjfx-dev 
<openjfx-dev-r...@openjdk.org><mailto:openjfx-dev-r...@openjdk.org> on behalf 
of John Hendrikx <john.hendr...@gmail.com><mailto:john.hendr...@gmail.com>
Date: Wednesday, September 11, 2024 at 19:05
To: openjfx-dev@openjdk.org<mailto:openjfx-dev@openjdk.org> 
<openjfx-dev@openjdk.org><mailto:openjfx-dev@openjdk.org>
Subject: Re: Proposal: Focus Traversal API

Hi Andy / List,

I've given this some thought first, without looking too much at the proposal.

In my view, focus traversal should be implemented using events, and FX should 
provide standard handling of these events controlled with properties 
(potentially even CSS stylable for easy mass changing of the default navigation 
policy).

## KeyEvent and TraversalEvent separation

I think the cleanest implementation would be to implement a KeyEvent listener 
on Scene that takes any unused KeyEvents, checks if they're considered 
navigation keys, and converts these keys to a new type of event, the 
TraversalEvent. The TraversalEvent is then fired at the original target. The 
TraversalEvent is structured into Directional and Logical sub types, and has 
leaf types UP/DOWN/LEFT/RIGHT and NEXT/PREVIOUS.  Scene is the logical place to 
handle this as without a Scene there is no focus owner, and so there is no 
point in doing focus traversal.

This separation of KeyEvents into TraversalEvents achieves the following:

- User can decide to act on **any** key, even navigation keys, without the 
system interfering by consuming keys early, unexpectedly or even consuming 
these keys without doing anything (sometimes keys get consumed that don't 
actually change focus...).  The navigation keys have many possible dual 
purposes, and robbing the user of the opportunity to use them due to an 
overzealous component interpreting them as traversal keys is very annoying.  
Dual purposes include for example cursor control in TextField/TextArea, 
Scrollbars, etc.  The user should have the same control here as these FX 
controls have.

- Scene is interpreting the KeyEvents, and this interpretation is now 
controllable.  If I want a Toolbar (or the whole application) to react to WASD 
navigation keys, then installing a KeyEvent handler at Scene level or at any 
intermediate Parent level that converts WASD to UP/LEFT/DOWN/RIGHT Traversal 
events would affect this change easily.

- The separation also allows to block Focus Traversal only, without blocking 
the actual Keys involved.  If I want to stop a Toolbar from reacting to 
LEFT/RIGHT, but I need those keys higher up in the hierarchy, then I'm screwed. 
 With the separation, the key events are unaffected, and I can block Toolbars 
from reacting specifically to traversal events only.

## Traversal Policy Properties on Parent

I think FX should provide several policies out of the box, based on common 
navigation patterns.  The goal here is to have policies in place that cover all 
use cases in current FX provided controls.  This will provide a good base that 
will cover probably all realistic work loads that custom controls may have. The 
goal is not to support every esoteric form of navigation, instead an escape 
hatch will be provided in the form of disabling the standard navigation.

In order to achieve this, I think Parent should get two new properties, which 
control how it will react to Directional and Logical navigation.  These will 
have default values that allow navigation to flow from Node to Node within a 
Parent and from Parent to its Parent when navigation options in a chosen 
direction are exhausted within a Parent.  Custom controls like Combo boxes, 
Toolbars, Button groups, etc, can change the default provided by a Parent 
(similar to how some controls change the mouse transparent flag default).

These two properties should cover all realistic needs, and IMHO should be 
considered to be CSS stylable in the future to allow easy changing of default 
policies of controls (ie. want all Toolbars to react differently to navigation 
keys, then just style the appropriate property for all toolbars in one go).

Parent will use these properties to install an event handler that reacts to 
TraversalEvents (not KeyEvents).  This handler can be fully disabled, or 
overridden (using setOnTraversalEvent).

- logicalTraversalPolicy
- directionalTraversalPolicy

The properties can be set with a value from a TraversalPolicy enum.  I would 
suggest the following options:

- OPEN

This policy should be the default policy for all Parents.  It will act and 
consume a given TraversalEvent only when there is a suitable target within its 
hierarchy.  If there is no suitable target, or the target would remain 
unchanged, the event is NOT consumed and left to bubble up, allowing its 
parent(s) to act on it instead.

- CONFINED

This policy consumes all TraversalEvents, regardless of whether there is 
something to navigate to or not.  This policy is suitable for controls that 
have some kind of substructure that we don't want to accidentally exit with 
either Directional or Logical navigation.  In most cases, you only want to set 
one of the properties to CONFINED as otherwise there would be no keyboard 
supported way to exit your control.  This is a suitable policy for say button 
groups, toolbars, comboboxes, etc.

- CYCLIC

Similar to CONFINED but instead of stopping navigation at the controls logical 
boundaries, the navigation wraps around to the logical start.  For example, 
when were positioned on the right most button in a button group, pressing RIGHT 
again would navigate to the left most button.

- IGNORED

This is similar to the mouseTransparent property, and basically leaves the 
TraversalEvent to bubble up.  This policy allows you to completely disable 
directional and/or logical navigation for a control.  Useful if you want to 
install your own handler (the escape hatch) but still want to keep either the 
default directional or logical navigation.

Possible other options for this enum could include a version that consumes all 
TraversalEvents (BLOCK) but I don't see a use for it at the moment.  There may 
also be variants of CONFINED and CYCLIC that make an exception for cases where 
there is only a single choice available.  A ButtonGroup for example may want to 
react differently depending on whether it has 0, 1 or more buttons.  Whether 
these should be enshrined with a custom enum value, or perhaps a flag, or just 
left up to a custom implementation is something we'd need to decide still.

## Use Cases
1) User wants to change the behavior of a control from its default to something 
else (ie. a Control that is CYCLIC can be changed to OPEN or CONFINED)

Just call the setters with the appropriate preferred policy.  This could be 
done in CSS for maximum convenience to enable a global change of all similar 
controls.

2) User wants to act on Traversal events that the standard policy leaves to 
bubble up

Just install a Traversal event handler either on the control or on its parent 
(depending on their needs).  A potential action to an unused Traversal event 
could be to close a Dialog/Toast popup, or a custom behavior like selecting the 
first/last item or next/previous row (ie. if I press "RIGHT" and there is no 
further right item, a user could decide to have this select the first item 
again in the current Row or the first item in the **next** Row).

3) User wants to do crazy custom navigation

Set both policies to IGNORED, then install your own event handler (or use the 
setOnTraversalHandler to completely override the handler).  Now react on the 
Traversal events, consuming them at will and changing focus to whatever control 
you desire.

4) User wants to change what keys are considered navigation keys

Install event handler on Scene (or any intermediate Parent) for KeyEvents, 
interpret WASD keys as UP/LEFT/DOWN/RIGHT and sent out a corresponding 
Traversal event

5) User wants to use keys that are considered navigation keys for their own 
purposes

Just install a KeyEvent handler as usual, without having to worry that 
Skins/Controls eat these events before you can get to them

6) User wants to stop a control from reacting to traversal events, without 
filtering navigation keys completely

With the separation of unconsumed KeyEvents into TraversalEvents, a user can 
now block only the latter to achieve this goal without having to blanket block 
certain KeyEvents.

-----

About the Proposal:

I think the Goals are fine as stated, although I think we differ on what the 
Traversal events signify.

I think CSS support should be considered a possible future goal.  The proposal 
should therefore take into account that we may want to offer this in the future.

Motivation looks okay.

> The focus traversal is provided by the FocusTraversal class which offers 
> static methods for traversing focus in various directions, determined by the 
> TraversalDirection enum.

I think these methods don't need to be exposed with a good selection of 
standard TraversalPolicy options.  After all, there are only so many ways that 
you can do a sensible navigation action without confusing the user, and 
therefore I think these policy options will cover 99% of the use cases already. 
 For the left over 1% we could **consider** providing these focus traversal 
functions as a separate public API, but I would have them return the Node they 
would suggest, and leave the final decision to call requestFocus up to the 
caller.  Initially however I think there is already more than enough power for 
custom implementations to listen to Traversal events and do their own custom 
navigation.  If it is not similar to one of the standard navigation options, 
the traverseUp/Down functions won't be of much use then anyway.

About your typical example:

    Node from = ...
    switch (((KeyEvent)event).getCode()) {
    case UP:
        FocusTraversal.traverse(from, TraversalDirection.UP, 
TraversalMethod.KEY);
        event.consume();
        break;
    case DOWN:
        // or use the convenience method
        FocusTraversal.traverseDown(from);
        event.consume();
        break;
    }

I think this is not a good way to deal with events.

1) The event is consumed regardless of the outcome of traverse.  What if focus 
did not change?  Should the event be consumed?

2) This is consuming KeyEvents directly, robbing the user of the opportunity to 
act on keys considered "special" by FX.

3) This code is not only consuming KeyEvents directly, but also deciding what 
keys are navigation keys.

So I think this example code should be different. However, first I expect that 
in most cases, configuring a different traversal policy on your Parent subclass 
will already be sufficient in almost all cases (especially if we look at FX 
current controls and see if the suggested policies would cover those use 
cases).  So this code will almost never be needed.  However, in the event that 
you need something even more specific, you may consider handling Traversal 
events directly.  In which case the code should IMHO look something like this:

    Node from = ...

    Node result = switch(traversalEvent.getEventType()) {
      case TraversalEvent.UP -> FocusTraversals.findUp(from);
      case TraversalEvent.DOWN -> FocusTraversals.findDown(from);
      // etc
   }

    if (result != null) {
         result.requestFocus();
         traversalEvent.consume();
    }

Note that the above code leaves the final decision to call requestFocus up to 
the caller.  It also allows the caller to distinguish between the case where 
there is no suitable Node in the indicated direction and act accordingly.

This allows it to NOT consume the event if it prefers its Parent to handle it 
(if the control doesn't want CYCLIC or CONFINED style navigation).  It also 
allows it to further scrutinize the suggested Node, and if it decides it does 
not like it (due to some property or CSS style or whatever) it may follow up 
with another findXXX call or some other option to pick the Node it wants.  It 
also allows (in the case of no Node being found) to pick its own preferred Node 
in those cases.  In other words, it is just far more flexible.

I'm not sure yet where to place these static helper methods (if we decide to 
expose them at all initially), or even if they should be static.  Given that 
its first parameter is always a Node, a non-static location for them could 
simply be on Node itself, in which case the calling convention would become 
"Node result  = from.findTraversableUp()" (suggested name only)

> Focus traversals generate a new type of event, encapsulated by the class 
> TraversalEvent which extends javafx.event.Event, using the event type 
> TraversalEvent.NODE_TRAVERSED.

What is the point of this event?  If you want to know that focus changed, you 
can add a listener to Scene.focusOwnerProperty.  What does it mean if I filter 
this event?  What if I consume it?  I don't think this should be an event at 
all, unless implemented as I suggested above, where 
consuming/filtering/bubbling can be used to control how controls will react to 
navigation events.

--John




On 03/09/2024 21:33, Andy Goryachev wrote:
Dear fellow developers:

I'd like to propose the public focus traversal API:


https://github.com/andy-goryachev-oracle/Test/blob/main/doc/FocusTraversal/FocusTraversal.md<https://urldefense.com/v3/__https:/github.com/andy-goryachev-oracle/Test/blob/main/doc/FocusTraversal/FocusTraversal.md__;!!ACWV5N9M2RV99hQ!LnjDXwUbbEymf9b1gkZFia8vuewsVJy6_49It-IKw66U9mS78PjdIPotBpc7AXlSfY7N5xcRXsmcPQhOzavk4z9VkPv-$>

Draft PR:

https://github.com/openjdk/jfx/pull/1555<https://urldefense.com/v3/__https:/github.com/openjdk/jfx/pull/1555__;!!ACWV5N9M2RV99hQ!LnjDXwUbbEymf9b1gkZFia8vuewsVJy6_49It-IKw66U9mS78PjdIPotBpc7AXlSfY7N5xcRXsmcPQhOzavk49fH_P2p$>

Your comments and suggestions will be warmly accepted and appreciated.

Thank you

-andy

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