+Visibility of MIME parts can be toggled
+
+ Each part of a multi-part MIME email can now be shown or hidden
+ using the button at the top of each part (by pressing RET on it or
+ by clicking). For emails with multiple alternative formats (e.g.,
+ plain text and HTML), only the preferred format is shown initially,
+ but other formats can be shown using their part buttons. To control
+ the behavior of this, see
+ `notmuch-multipart/alternative-discouraged` and
+ `notmuch-show-all-multipart/alternative-parts`.
+