Is another text editor needed? Sublime Text isn't bad. And to be honest, the main reason that I wrote Luan Editor was to learn Java Swing. But now that it is finished, I rather like it.
Luan Editor requires Java (JDK) 8, so you must install this first. It also requires Bash. Once these are working, you can download the tar file and install it. Then you can run luan_editor from the command line.
The downloads list also includes installers for Mac and Windows. I made these to learn how to make installers for Luan apps. They are otherwise useless.
Luan Editor is open source and is written in Luan.