Using HIME(http://hime.luna.com.tw/) as a system status icon, instead a message tray.
usage:
cd ~/.local/share/gnome-shell/extensions/
git clone git://github.com/dieterhsu/gnome-shell-extension-hime.git [email protected]
Enable this extension on gnome-tweak-tool, then press ALT+F2, r, enter to restart gnome-shell or relogin