Upgrade the minimum required GTK version for JavaFX to GTK 3.20 to enable modern features and better Linux desktop integration.
JavaFX currently depends on GTK 3.8, [released](https://mail.gnome.org/archives/gtk-devel-list/2013-March/msg00108.html) in March 2013. This version is outdated and predates many useful GTK API improvements. GTK 3.20 was [released](https://mail.gnome.org/archives/gtk-list/2016-March/msg00026.html) on March 21, 2016. Updating the GTK minimum requirement to 3.20 would enable JavaFX to support new features, including the improvements proposed in #1605 Major Linux distributions already provide GTK 3.20 or newer: - Ubuntu LTS 18.04+ (ships GTK 3.22+) - Debian 9+ (ships GTK 3.22+) - Fedora 24+ (ships GTK 3.20+) - Oracle Linux and Red Hat Enterprise Linux 8+ (ships GTK 3.22+) ------------- Commit messages: - Remove return - Require Gtk 3.20 Changes: https://git.openjdk.org/jfx/pull/1825/files Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=1825&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8359396 Stats: 61 lines in 3 files changed: 36 ins; 23 del; 2 mod Patch: https://git.openjdk.org/jfx/pull/1825.diff Fetch: git fetch https://git.openjdk.org/jfx.git pull/1825/head:pull/1825 PR: https://git.openjdk.org/jfx/pull/1825
