Precise behavior of function-key-map and friends

[Stefan Monnier]

1 - The documentation says that function-key-map bindings only apply
  if there is no corresponding binding in the global map.

  What about the case where I have a function-key-map binding that
  turns C-x into C-c.  Clearly C-x C-c will stays as it is, but
  what about C-x w (which has no binding) ?

  Currently C-x w is left as is.  Should function-key-map remap it
  to C-c w ?

2 - key-translation-map says that the translation is always done, whether
  or not it has a binding in the normal maps.
  Among other things, this means that when you hit C-x 8 it will
  keep reading input because there's a chance that it will end up
  in a sequence of keys that can be translated by key-translation-map.
  So you can hit C-c C-x 8 ' e to enter the (unbound) C-c é key sequence.
  But note that C-x C-x 8 ' e does not work, because C-x C-x is bound
  and read-key-sequence will not keep reading input in this case.

3 - function-key-map applies only if the current key-sequence has
  no binding in the normal maps.  But since key-translation-map
  is applied unconditionally afterwards, the "has a binding" condition
  is not easy to decide (and is done incorrectly).  E.g. say I have
  a function-key-mapping from X to Z and a key-translation-mapping from
  X to Z and from Z to X.
  If there's a global key binding for Z but not for X, a keyboard
  entry of X will be function-key-mapped to Z and then
  key-translation-mapped to X and the result will be "ding".
  OTOH if there's a binding for X but not for Z, the X entry
  will not be function-key-mapped, so it will be key-translation-mapped to Z
  and there again, the result will be "ding".


        Stefan