# [isabelle-dev] Isabelle_11-Sep-2011

Fri Sep 30 16:21:27 CEST 2011

Dear Makarius and René,

> >However, testing Isabelle_20-Sep-2011 with Emacs 23.3, there seems to be a problem for Mac OS Lion users:
> >Many special characters like ==> \in, => are not displayed correctly which makes working inconvenient. Under
> >
> >http://cl-informatik.uibk.ac.at/~thiemann/emacs.html

I believe I know this bug. It's an emacs problem, and should be fixed in
emacs 23.4 once it becomes available. That said I don't know of any elisp
code other than ProofGeneral that tickles this bug. As far as Isabell/PG
are concerned, it's not a new problem -- it also affects Isabelle2011. See

http://debbugs.gnu.org/cgi/bugreport.cgi?bug=8703

(Note that I encountered this problem with Linux -- I hope that the MacOS
version uses the same code, but I have not tested this theory.)

Best regards,

Bertram