RFR: 8313424: JavaFX controls in the title bar [v65]

[Michael Strauß]

On Thu, 24 Apr 2025 15:01:24 GMT, Markus Mack <mmack at openjdk.org> wrote:

>> I agree when it actually makes a semantic difference. For example, there's a difference between setting `Node.opacity` to zero, and setting `Node.visible` to `false`. In the first case, the node will still receive events, while in the second case it won't. But what's the semantic difference between non-existing header buttons, and header buttons with zero height?
>> 
>> One argument against setting `prefButtonHeight` to zero could be that it special-cases one specific value (or two, because there's also the special value `USE_DEFAULT_SIZE`). In general, the property only describes a _preferred_ height, which the toolkit is free to honor (in any way it sees fit) or to ignore entirely. However, the two special values 0 and `USE_DEFAULT_SIZE` are specified to be honored by all toolkits in all cases.
>
> Typically it's issues related to keyboard navigation that forget to handle the zero-size case. But I agree it's ok to leave it as it is because it's documented in a way that can be trusted.

That's true, but in this specific case, header buttons are not focus-traversable or visible to accessibility APIs (unlike regular buttons in the scene graph).

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PR Review Comment: https://git.openjdk.org/jfx/pull/1605#discussion_r2058683097