As requested and discussed before I made a notification area plugin for GTG. This allows you to click on the notification area icon to “minimize” GTG. It also has a small context menu. Keep in mind that if you minimize GTG it will minimize normally (it will not “disappear”), this plugin does not change GTG’s UI or how it works.

Anyway You should read Lionel’s article on “There’s no tray icon in GNOME!“. It is a MUST READ!

The plugin is available in the current development branch.