replMain doesn't exit when windows are closed

Sorry, one more replMain issue.  When you're using it and you close the last window, the program's still running and you have to ctrl-c out to get back to the repl.  If you run main instead, exiting the last window exits the program all the way back to the repl.  It's a minor nit, but I just noticed it.  I can reproduce this in hello-world in 0.8.0.2.  Apologies if this is known/accepted behavior.