Glimmer DSL for SWT 4.21 (New SWT/JRuby/JDK)

Glimmer DSL for SWT 4.21 is the quarterly major release that ships with a new version of SWT (released in 2021-09) as well as other big changes like JRuby 9.3.0.0 and JDK 16:

• Upgrade to SWT 4.21
• Upgrade to JDK 16.0.2
• Upgrade to JRuby 9.3.0.0
• Update packaging to rely on JDK 16 `jpackage` (instead of older JDK 8 `javapackager`)
• Renamed `Glimmer::RakeTask::Package.javapackager_extra_args` to `Glimmer::RakeTask::Package.jpackage_extra_args` to match the name of `jpackage` in JDK 16
• Change `package/[os]` scaffolding placement for packaging icons into `icons/[os]` to accomodate Java 9 Module security for icon retrieval from within a JAR

The biggest difference in this version of SWT is auto-switching to Dark Mode on the Mac.

If you encounter any issues due to the big upgrade from JDK 8 to JDK 16 and jpackage for native-executable packaging, please report in an issue request. There is one annoying message that shows up during packaging with Warbler (unsupported Java version "16", defaulting to 1.7), which seems caused by running JRuby on JDK 16, but I was able to contain its damage and render it harmless (at least as far as I could tell).

In other news, a new Glimmer DSL has been brewing:

Glimmer DSL for LibUI is a prerequisite-free CRuby desktop development GUI library. No need to pre-install any prerequisites. Just install the gem and have platform-independent native GUI that just works!

Happy Glimmering!