mu4e: add mu4e-view-toggle-html

Add `mu4e-view-toggle-html' for toggling between html and text display
of messages (when available); keybinding 'h'. Document this.

The new default keybinging for mu4e-view-toggle-hide-cited becomes '#'.

NEWS.org

@@ -42,6 +42,11 @@
      behavior.
    - overwrite target message files that already exist, rather than
      erroring out.
+   - set mu4e-view-html-plaintext-ratio-heuristic to 5, as 10 was too
+     high to detect some effectively html-only messages
+   - add mu4e-view-toggle-html (keybinding: 'h') to toggle between
+     text and html display. The existing 'mu4e-view-toggle-hide-cited'
+     gets the new binding '#'.
 
 ** 0.9.13
 

mu4e/mu4e-view.el

@@ -640,7 +640,8 @@ FUNC should be a function taking two arguments:
 
       ;; misc
       (define-key map "w" 'visual-line-mode)
-      (define-key map "h" 'mu4e-view-toggle-hide-cited)
+      (define-key map "#" 'mu4e-view-toggle-hide-cited)
+      (define-key map "h" 'mu4e-view-toggle-html)
       (define-key map (kbd "M-q") 'mu4e-view-fill-long-lines)
 
       ;; next 3 only warn user when attempt in the message view
@@ -663,6 +664,8 @@ FUNC should be a function taking two arguments:
 	(define-key menumap [sepa0] '("--"))
 	(define-key menumap [wrap-lines]
 	  '("Toggle wrap lines" . visual-line-mode))
+	(define-key menumap [hide-cited]
+	  '("Toggle view-html" . mu4e-view-toggle-html))
 	(define-key menumap [hide-cited]
 	  '("Toggle hide cited" . mu4e-view-toggle-hide-cited))
 	(define-key menumap [raw-view]
@@ -704,8 +707,6 @@ FUNC should be a function taking two arguments:
 	  '("Search bookmark" . mu4e-headers-search-bookmark))
 	(define-key menumap [jump]
 	  '("Jump to maildir" . mu4e~headers-jump-to-maildir))
-	(define-key menumap [refresh]
-	  '("Refresh" . mu4e-headers-rerun-search))
 	(define-key menumap [search]
 	  '("Search" . mu4e-headers-search))
 
@@ -917,6 +918,12 @@ the new docid. Otherwise, return nil."
     (mu4e-view-refresh)
     (mu4e~view-hide-cited)))
 
+(defun mu4e-view-toggle-html ()
+  "Toggle html-display of the message body (if any)."
+  (interactive)
+  (setq mu4e-view-prefer-html (not mu4e-view-prefer-html)) 
+  (mu4e-view-refresh)) 
+
 (defun mu4e-view-refresh ()
   "Redisplay the current message."
   (interactive)

mu4e/mu4e.texi

@@ -1191,8 +1191,10 @@ misc
 ----
 ;            switch focus
 c            copy address at point (with C-u copy long version)
+
+h            toggle between html/text (if available)
 w            toggle line wrapping
-h            toggle showing cited parts
+#            toggle showing cited parts
 
 v            show details about the cryptographic signature
 
@@ -1267,13 +1269,16 @@ is used for images.
 @node Displaying rich-text messages
 @section Displaying rich-text messages
 
-@t{mu4e} normally prefers the plain-text version for messages that consist of
-both a plain-text and html (rich-text) versions of the body-text. You can
-change this by setting @code{mu4e-view-prefer-html} to @t{t}.
+@t{mu4e} normally prefers the plain-text version for messages that
+consist of both a plain-text and html (rich-text) versions of the
+body-text. You can change this by setting @code{mu4e-view-prefer-html}
+to @t{t}. And you can toggle this value (globally) using @kbd{h} in the
+message view; this also refreshes the message with the new setting.
 
 If there is only an html-version, or if the plain-text version is too
-short in comparison with the html part@footnote{this is for the case
-where the text-part only warns that you should use the html-version},
+short in comparison with the html part@footnote{this is e.g. for the
+case where the text-part is only a short blurb telling you to use the
+html-version; see @code{mu4e-view-html-plaintext-ratio-heuristic}},
 @t{mu4e} tries to convert the html into plain-text for display.
 
 The default way to do that is to use the @command{emacs} built-in