RFR: 8313424: JavaFX controls in the title bar [v71]

[Cormac Redmond]

On Sat, 3 May 2025 08:35:15 GMT, Michael Strauß <mstrauss at openjdk.org> wrote:

>> I imagine most people will want HeaderBar's leading node to be an app icon with the usual left-click context menu behaviour (i.e., at least restore, minimise, close), much like it is for DECORATED today.
>> 
>> Today, you can add a bunch of icons to a stage with stage.getIcons().addAll(myLogoList)), and the window's header will contain a suitable icon; never too big, never too small. The developer doesn't worry about it.
>> 
>> I really feel a utility to add an equivalent app icon to the HeaderBar, should be provided out-of-the-box, using the same logic. E.g., let HeaderBar choose the most suitable icon, and choose the correct size for the platform, and any padding, etc. Otherwise, the developer needs to think about it too much.
>> 
>> A lot of this logic used by DECORATED, seems to be buried in WindowStage in terms of picking what icons to display in the title bar, etc.
>
> @credmond
> I think we run the risk of overloading `HeaderBar` with too many narrow features. Here are a few observations:
> 1. Modern applications tend to not use program icons. Windows Explorer, Calendar, Weather, Settings, and also Spotify or Chrome don't use it. Program icons have become more of a Win32-era relict, and it's mostly applications that use system-decorated windows that have it.
> 2. Program icons are really only a thing on Windows. It doesn't seem to make much sense to have a Windows-only API on a multi-platform toolkit. It certainly doesn't work with macOS, as we have the traffic lights in front of the leading node of the `HeaderBar`.
> 3. It's very easy to create a program icon with standard JavaFX controls. Since its size will never change, you can just use a static image with an `ImageView` and a `ContextMenu`. JavaFX already supports multi-resolution images out of the box (with the `@Nx` file name convention).
> 4. If you choose to have a program icon, you most likely want it to align nicely with the rest of your custom header bar. Even in apps that have a program icon, it's not a one-size-fits-all (for example, the IntelliJ program icon looks significantly different than a standard system-decorated program icon). Once you start to customize the program icon, you're really better off just using standard JavaFX controls to do the job.

Thanks for the detailed reply @mstr2. I can't really argue with any of your points, I also agree.

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PR Comment: https://git.openjdk.org/jfx/pull/1605#issuecomment-2848565539