what is the recommended way to customize print-backtrace, e.g. with
Currently the comment seems to disagree with the code about whether
some overrides apply to arg printing in backtraces or not.
See the attached patch for one way to handle this: it basically copies
the *debug-print-variables-alist* mechanism, thus preserving the
current behaviour while still allowing full customizability.
Also, what about introducing mechanisms to allow the user to print
only selected frames, like :end-if to cut off a stack at some known