Most (if not all) keys available in folder mode are also available in show mode. The missing exception is "p" for mh-show-pack-folder. The defun is there to redirect the call to mh-pack-folder so I can only assume this is an inadvertent omission.
Patch being committed
This covers one aspect mentioned in SF #2828704.
committer: Jeffrey C Honig <email@example.com>
branch nick: mh-e
timestamp: Tue 2011-12-27 12:13:50 -0500
(mh-show-folder-map): Add missing key binding for mh-show-pack-folder
(closes SF #3466086).