Bugfix: Help menu not working

Related to PR #3150 
Above mentioned PR fixed the issue of the disappearing help menu items, but the 'first level' help menu items (i. e. in the main application menu bar) didn't work anymore (no ActionListeners were attached to them). Sorry, didn't notice that earlier when reviewing the PR.

Test: Make sure the help menu items in the main application menu are working.

/cc @jburel