I'm experiencing a weird issue on OS X where command mode in Vintage is simply not accessible. Esc, ctrl+[, etc. do not get me out of insert mode into command mode, and setting vintage_start_in_command_mode to true also has no effect. I *think* this has been happening since I upgraded to Mountain Lion, but that may just be a coincidence; I don't use this system all of the time so I'm not sure exactly when the problem started happening. How do I go about debugging this?