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I'm on Mac OS X, Version 10.8, if that matters. Could try to repro on a linux box, if it'd be helpful, but not for a few days.

I'm on Version 2.0.1, build 2217.

I have a file open. I'm right clicking on the file in the Folders dropdown on the left, renaming it from init.pp (for which there is no syntax highlighting) to init.rb. The syntax highlighting doesn't change until I close the file and reopen it, after which everything works perfectly.