RFR: 8366369: Add @requires linux for GTK L&F tests

[Sergey Bylokhov]

On Tue, 2 Sep 2025 17:17:26 GMT, Alexey Ivanov <aivanov at openjdk.org> wrote:

>It should be tested on Unix-like systems if and only if GTK library is supported.

You’re excluding that possibility by using "@requires=linux". Instead, it should be handled the same way we check for other features like tray icon or multimonitor support by performing the check at the start of the test and exiting if the feature is not supported. You can exclude Windows and macOS but left other platforms as is.

>If GTK library isn't supported (or available) on a system, I see no reason in wasting time and even starting the test. It's the purpose of @requires expression that can be amended to include other platforms where GTK library is supported and, therefore, GTK Look-and-Feel can be instantiated.

We do not have "requires" for gtk, the "headful" and "linux" tags added to the tests are unrelated to the gtk.

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PR Review Comment: https://git.openjdk.org/jdk/pull/26995#discussion_r2316782166