Allow to set the reply policy in a smart manner

Depending on whether the original email was encrypted, one can set
different reply policies.

mu4e/mu4e-compose.el

@@ -146,7 +146,7 @@ Also see `mu4e-context-policy'."
 	   :group 'mu4e-compose))
 
 
-(defcustom mu4e-compose-crypto-reply-policy 'sign-and-encrypt
+(defcustom mu4e-compose-crypto-reply-encrypted-policy 'sign-and-encrypt
   "Policy for signing/encrypting replies to encrypted messages.
 We have the following choices:
 
@@ -162,6 +162,22 @@ We have the following choices:
 	   :safe 'symbolp
 	   :group 'mu4e-compose))
 
+(defcustom mu4e-compose-crypto-reply-plain-encrypted-policy 'sign  "Policy for signing/encrypting replies to encrypted messages.
+We have the following choices:
+
+- `sign': sign the reply
+- `sign-and-encrypt': sign and encrypt the reply
+- `encrypt': encrypt the reply, but don't sign it.
+-  anything else: do nothing."
+  :type '(choice
+	   (const :tag "Sign the reply" sign)
+	   (const :tag "Sign and encrypt the reply" sign-and-encrypt)
+	   (const :tag "Encrypt the reply" encrypt)
+	   (const :tag "Don't do anything" nil)
+	   :safe 'symbolp
+	   :group 'mu4e-compose))
+
+
 (defcustom mu4e-compose-format-flowed nil
   "Whether to compose messages to be sent as format=flowed (or
    with long lines if `use-hard-newlines' is set to nil).  The
@@ -525,13 +541,23 @@ buffers; lets remap its faces so it uses the ones for mu4e."
 
 (defun mu4e~compose-crypto-reply (parent compose-type)
   "When composing a reply to an encrypted message, we can
-automatically encrypt that reply."
-  (when (and  (eq compose-type 'reply)
+automatically encrypt that reply. When the message is unencrypted, 
+we can decide what we want to do."
+  (message "%S %S" parent compose-type)
+  (if (and  (eq compose-type 'reply)
 	  (and parent (member 'encrypted (mu4e-message-field parent :flags))))
-	(case mu4e-compose-crypto-reply-policy
+	(case mu4e-compose-crypto-reply-encrypted-policy
 	  (sign (mml-secure-message-sign))
 	  (encrypt (mml-secure-message-encrypt))
-	  (sign-and-encrypt (mml-secure-message-sign-encrypt)))))
+	  (sign-and-encrypt (mml-secure-message-sign-encrypt))
+	  (message "Do nothing"))
+	(case mu4e-compose-crypto-reply-plain-policy
+	  (sign (mml-secure-message-sign))
+	  (encrypt (mml-secure-message-encrypt))
+	  (sign-and-encrypt (mml-secure-message-sign-encrypt))
+	  (message "Do nothing")))
+  )
+
 
 (defun* mu4e~compose-handler (compose-type &optional original-msg includes)
   "Create a new draft message, or open an existing one.