This PR deprecates the JavaFX glass GTK 2 library for removal. Since there isn't an associated API, the mechanism for doing this is to print a "deprecated for removal" warning message when the `glassgtk2` library it is loaded. A message is printed regardless of why the GTK 2 library was loaded, which can happen for one of the following reasons:
1. The application or end user has explicitly requested GTK 2 using the `jdk.gtk.version` system property. 2. Another native library has already loaded the GTK 2 library (an application cannot load both the GTK 2 and GTK 3 libraries in the same process) 3. As a fallback if the gtk3 libraries are not available on the system. The warning messages are patterned after the security manager deprecation messages added as part of [JEP 411](https://openjdk.java.net/jeps/411). I added two system tests, one that sets the `jdk.gtk.version` system property to `2` and verifies that the warning message is printed, and one that doesn't set `jdk.gtk.version` and verifies that no warning message is printed. ------------- Commit messages: - 8273089: Deprecate JavaFX GTK 2 library for removal Changes: https://git.openjdk.java.net/jfx/pull/685/files Webrev: https://webrevs.openjdk.java.net/?repo=jfx&pr=685&range=00 Issue: https://bugs.openjdk.java.net/browse/JDK-8273089 Stats: 221 lines in 4 files changed: 221 ins; 0 del; 0 mod Patch: https://git.openjdk.java.net/jfx/pull/685.diff Fetch: git fetch https://git.openjdk.java.net/jfx pull/685/head:pull/685 PR: https://git.openjdk.java.net/jfx/pull/685
