Docker = A KDE System Tray for Openbox 2
https://icculus.org/openbox/2/docker/
Docker is a docking application (WindowMaker dock app) which acts as a system tray for KDE and GNOME2. It can be used to replace the panel in either environment, allowing you to have a system tray without running the KDE/GNOME panel or environment.
Docker is written and designed to work with [Openbox 2](https://icculus.org/openbox/2/), but it should work fine in any window manager that supports `WindowMaker` dock apps. If you running `WindowMaker` or otherwise and experiencing problems, you should try using the `-wmaker` option to make docker keep a fixed size.