This was a cool little feature added by Caolán in , but from GNOME 3.32 on, it will effectively become dead code.
From GNOME 3.30’s release notes:
“From 3.32, application menus will no longer be shown in the GNOME 3 top bar, and application developers are recommended to remove their application menus in time for GNOME 3.32” 
GNOME designers have *finally* realized what an usability nightmare this design was.
Caolán: thought you may be interested in the discussion here.
fine by me, I don't object
(In reply to Caolán McNamara from comment #2)
> fine by me, I don't object
Caolán, do you think this could be turned into an easyHack ?
yeah, its suitable and the original link points to the relevant code to remove so its straightforward IMO
To revert these changes, go though the list of commits provided above and run `git revert` for each one top-to-bottom (that is in reverse chronological order). That is:
git revert b163772e77e64261b62a9e8196799a499e4ef77d
git revert 4843d5e8865d2f63f408f464e28be9440cb1ecc2
Resolve any conflicts and ensure the result builds still ;) (might be done on gerrit)
Arkadiy Illarionov committed a patch related to this issue.
It has been pushed to "master":
Resolves: tdf#119996 remove support for GNOME Shell application menu
It will be available in 6.3.0.
The patch should be included in the daily builds available at
https://dev-builds.libreoffice.org/daily/ in the next 24-48 hours. More
information about daily builds can be found at:
Affected users are encouraged to test the fix and report feedback.