This is more of a general annoyance. Every time after stopping the simulator, Xcode jumps to main.m for some reason. On the left nav, it jumps to the Debug Navigator.
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I guess it's fair to call it a bug, Xcode 3 specifically suppressed this useless artefact.
I've had success (four times and counting) with this one-liner in ~/.gdbinit:
handle SIGKILL nostop noprint nopass
Taken from this gdb manual:
http://www.delorie.com/gnu/docs/gdb/gdb_39.html
Not sure if it applies to lldb as well.