Glimmer DSL for SWT 126.96.36.199 has shipped with explicit system tray support (was implicitly supported via SWT before), greatly simplifying the addition of a tray item to a desktop app.
The Hello, Tray Item! sample demonstrates the details.
Hello, Tray Item! Icon [white circles on a black square] (clicking or right clicking brings up a menu that allows showing About dialog, hiding and showing app, and exiting completely)
Hello, Tray Item! App
Hello, Tray Item! About Message Box
Hello, Canvas Animation!
Hello, Canvas Animation Multi!