I have been making some cosmetic changes to the theme. So far I have changed the users.png image, the title, the "free" text and welcome text.
I think I have found where the sidebar width is defined:
themes/facebook/plugins/default/css/core/default.css -- line 618
however, changes here do not alter the page in my browsers. I have gone up to 280, from 200 and even restarted the server after making the change.
The menu has a scrollbar so it needs to be a little wider.