Setting graphics of a Labeled does not show the Label correctly

[Michael Strauß]

There's a larger picture here: from a user perspective, there's a
difference between the scene graph and the "document graph".
The document graph is what users actually work with, for example by
setting the `Labeled.graphic` property. In some cases, document nodes
don't correspond to scene nodes at all (`MenuItem` or `Tab` come to
mind).
The document graph is later inflated into a scene graph of unknown
structure (because skins are mostly black boxes with regards to their
internal structure).

I've proposed an enhancement that would make the document graph a
first-class citizen:
https://mail.openjdk.org/pipermail/openjfx-dev/2022-June/034417.html

With this in place, we could simply disallow the same node appearing
multiple times in the document graph, which would not only solve the
problem for `Labeled`, but for all controls with a similar problem.


On Thu, Dec 1, 2022 at 6:17 PM John Hendrikx <john.hendrikx at gmail.com> wrote:
>
> The mechanism does seem like it is a bit poorly designed, as it is easy to create inconsistencies.
>
> Luckily it seems that you can't remove a graphic yourself from a Control (getChildren is protected).
>
> I don't think there is an easy solution though...
>
> I think that once you set a graphic on a Labeled, you need to somehow mark it as "in use".  Normally you could just check parent != null for this, but it is trickier than that.  The Skin ultimately determines if it adds the graphic as child, which may be delayed or may even be disabled (content display property is set to showing TEXT only).
>
> Perhaps Skins should always add the graphic and just hide it (visible false, managed false), but that's going to be hard to enforce.
>
> Marking the graphic as "in use" could be done with:
>
> - a property in `getProperties`
> - a new "owner" or "ownedBy" property
> - allowing "parent" to be set without adding it to children (probably going to mess up stuff)
>
> --John