RFR: 8313424: JavaFX controls in the title bar [v11]

[Michael Strauß]

On Mon, 28 Oct 2024 09:23:50 GMT, Thiago Milczarek Sayao <tsayao at openjdk.org> wrote:

> The current behavior is do adapt to Scene background.
> 
> As it does not fit all scenarios, I would not adapt it at all, and provide a way to developers to CSS style the Window Controls overlay.

There are good reasons to adapt the window button theme to the Scene background, most importantly because it is easily specified and easily documented.

Allowing developers to customize the styling of the window buttons would increase the specification surface of this new feature dramatically:
1. We would have to specify the `WindowControlsOverlay` control and its substructure, as well as its style classes and pseudoclasses.
2. We would need a new API to set the window buttons stylesheet on a Stage.

I don't think that this is necessarily a bad idea, maybe we should even do that in the future. But in the interest of getting this feature across the finish line, I think we should keep the scope as small as possible and add more features in subsequent enhancements.

In particular, customizing the window buttons stylesheet requires a good way for developers to specify different colors for dark and light themes. Currently there is no good way to do this purely with CSS. The current implementation uses a `dark` style class that is set on the window buttons for dark themes.

However, I really don't want to make this public, because having a `dark` style class is not a good solution. There's only one way to do this right, and it is with supporting the `prefers-color-scheme` media query.

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PR Comment: https://git.openjdk.org/jfx/pull/1605#issuecomment-2442251975