RFR: 8375578: Enable translucent window backdrops

[Michael Strauß]

On Thu, 22 Jan 2026 18:50:48 GMT, Martin Fox <mfox at openjdk.org> wrote:

>> Should we have a (new kind of) fallback system, or should we do this with the existing `Platform.isSupported(ConditionalFeature)` and have the user decide based on the result of that function?
>
> I agree that an enum is inadequate. The two API's we have to work with (macOS and Win11) are based on enums; you specify the type of window or content (e.g. tooltip, menu, sidebar, window) and let the OS decide what material to use. macOS pro-actively enumerates a lot of different window types though it looks like many of them map to the same material under the hood. I'm not entirely sure the glass effect recently added to macOS is appropriate for JavaFX but it is a prime example of a specialized platform-specific backdrop that can't easily be squeezed into an enum.
> 
> So, yes, we should expand StageBackdrop so we can provide more information. How to do that might be beyond my pay grade (I'm not a Java expert). I don't think the existing `Platform.isSupported()` API would be appropriate since it takes a separate enum type.

> Should we have a (new kind of) fallback system, or should we do this with the existing `Platform.isSupported(ConditionalFeature)` and have the user decide based on the result of that function?

Expanding on that question: if we have platform-specific backdrops that may have a big impact on styling and readability, stylesheets may want to query the actual backdrop used via media queries.

-------------

PR Review Comment: https://git.openjdk.org/jfx/pull/2048#discussion_r2718194820