Take a walk on the client side with Qt Jambi -- an alternative to Swing and Java 2D for developing rich, cross-platform desktop-application interfaces.

SWTBot and Marathon are both applications to write GUI tests for Java applications. SWTBot uses Java and is thus potentially usable with JRuby.

Java revolutionized software development 30 years ago. Even with the rise of web apps, there's a bright future for Java desktop application development.

Web applications may be written in pure Java, or a mix of Java and HTML. Vaadin's components are web components self-described as mobile-first, fine-tuned for UX, performance, and accessibility.

Amazon's early approach to hybrid HTML5 Android app development may not have been a straight path, but according to their director of app developer services, Ethan Evans, the process taught volumes.

However, GUI support isn’t scheduled to arrive until later this year, likely with the Windows 10 Fall 2020 Update (or whatever Microsoft settles on for a name).