Comment 10 for bug 1424843

This is a workaround, *not* a solution, for Ubuntu. Goto source code gajim/data/gui/application_menu.ui, add the keyboard shortcut (control-u) to the Plugins menu action "app.plugins" (search for "app.plugins"):
<attribute name="accel">&lt;Primary&gt;U</attribute>
then You can open the plugins menu with ctrl-u.
Other interesting shortcuts in the appmenu are: accounts (shift-ctrl-a), new chat (ctrl-n), group chats (ctrl-b), settings (ctrl-p), quite (ctrl-q)