Font color of the contact varies depending on the chat state.
The plugin does not work if you use custom font color for contacts in roster.
More info in ticket #3628
You can use special plugin, that manages automatic download and installation of others plugins, it is called Plugin Installer.
Download the [/raw-attachment/wiki/ChatstatePlugin/chatstate.zip zip file] and install it directly from Gajim
Existing bugs and feature requests are [query:?status=accepted&status=assigned&status=new&status=reopened&component=ChatstatePlugin here].
If you have any issues, create a [/newticket?component=ChatstatePlugin&owner=Dicson new ticket].