I wonder if there should be some option to completely turn off undo, so you're not deep in some production django shell deleting data or something and then instinctively hit ctrl-r because you made a typo, accidentally deleting more than you wanted to. (in this case, you should have access to some weak undo (#328) that is only used for editing lines in a single buffer). I don't find myself in this use case in bpython, but can imagine it. This is already possible with a config - just set undo to no hotkey - but several configs can't be combined so if django were to set a config for bpython the user's config would no longer be respected.