Dictionary won't open

When I click on “Dictionary” (I think it’s in the category “Edit -> Writing Tools”, but I’m using the German version where it’s “Bearbeiten -> Schreibwerkzeuge”), nothing happens. When I try the hotkey combos shown there either nothing happens (CTRL+G) or the search for formatting opens (CTRL+F3).
I think the second hotkey combo doesn’t belong there anyway.