`mime-preview-toggle-header' to "\C-c\C-t\C-h".
(define-key mime-view-mode-map
"\C-c\C-p" (function mime-preview-print-current-entity))
(define-key mime-view-mode-map
- "\C-ch" (function mime-preview-toggle-header))
+ "\C-c\C-t\C-h" (function mime-preview-toggle-header))
(define-key mime-view-mode-map
"a" (function mime-preview-follow-current-entity))
(define-key mime-view-mode-map