Implement a screenshot command for Message mode

* doc/misc/message.texi (MIME): Document it.

* lisp/gnus/message.el (message-screenshot-command): New variable.
(message-mode-map): New keystroke and menu item.  Also add
mml-attach-file to the menu.
(message-insert-screenshot): New command.

* lisp/gnus/mml.el (mml-parse-1): Allow having
content-transfer-encoding already in the part, so that we can have
inline base64-encoded binaries in the Message buffers.

1 files changed, 12 insertions, 0 deletions

diff --git a/doc/misc/message.texi b/doc/misc/message.texi
index bdd31b1fe49..7a66422b17e 100644
--- a/doc/misc/message.texi
+++ b/doc/misc/message.texi
@@ -883,6 +883,18 @@ is a list, valid members are @code{type}, @code{description} and
 @code{nil}, don't ask for options.  If it is @code{t}, ask the user
 whether or not to specify options.
 
+@vindex message-screenshot-command
+@findex message-insert-screenshot
+@cindex screenshots
+@kindex C-c C-p
+If your system supports it, you can also insert screenshots directly
+into the Message buffer.  The @kbd{C-c C-p}
+(@code{message-insert-screenshot}) command inserts the image into the
+buffer as an @acronym{MML} part, and puts an image text property on
+top.  The @code{message-screenshot-command} variable says what
+external command to use to take the screenshot.  It defaults to
+@code{"import png:-"}, which is an ImageMagick command.
+
 You can also create arbitrarily complex multiparts using the @acronym{MML}
 language (@pxref{Composing, , Composing, emacs-mime, The Emacs MIME
 Manual}).