How can I see the Vidalia Control Panel on the Mac? It used to open first, and then stay open when the browser opened. Now it only flicks up briefly, and then disappears.
Vidalia is no longer part of the Tor Browser bundle. Instead, the most important functionality of Vidalia has been integrated with Tor Browser itself. So perhaps what you are seeing is that the connection preferences dialog of Tor Browser disappears once you've given it enough information for Tor Browser to make a connection to the Tor network.
See also the question What happened to Vidalia?