Comment 26 for bug 1806292

Caolán McNamara committed a patch related to this issue.
It has been pushed to "libreoffice-6-2":

https://git.libreoffice.org/core/+/da9e424c556e25cf42eddc9d6fa22011e80359aa%5E%21

tdf#116290 allow menubar to shrink past its minimum size

It will be available in 6.2.0.1.

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:
https://wiki.documentfoundation.org/Testing_Daily_Builds

Affected users are encouraged to test the fix and report feedback.