"'" mh-show-narrow-to-tick
"?" mh-prefix-help
"c" mh-show-narrow-to-cc
- "f" mh-show-narrow-to-from
- "r" mh-show-narrow-to-range
+ "g" mh-show-narrow-to-range
+ "m" mh-show-narrow-to-from
"s" mh-show-narrow-to-subject
"t" mh-show-narrow-to-to
"w" mh-show-widen)