Hi, For some reason, the patch that is supposed to fix vertical panel issues had been dropped [1] at some point. The related bug report [2] had been reopened. I guess the patch needs to be reintroduced (not sure why Martin mentioned it's obsolete)...
[1] http://anonscm.debian.org/cgit/pkg-mate/mate-panel.git/commit?id=c24fde378b7aca3ad7c19c2410b64ca11dfb06bf [2] https://bugs.debian.org/785272
