Tails 0.12.1, opening Vidalia 0.2.17 to browse the 'Message Log' reveals no log at all.

The log file is generated in /var/log/tor but there's no output in Vidalia.

The default settings in Vidalia makes it only show warnings, notices and errors, and if Tor issues none of them after Vidalia has started, it won't show anything. If you want to see something, just to verify that it works, send a HUP to Tor:

sudo kill -HUP $(pidof tor)
Comment by Tails Fri 10 Aug 2012 12:35:46 PM CEST