bug#37592: Using tabs in EWW

[Juri Linkov]

>> > Instead of adding another defcustom, how about doing this by default
>> > if tab-bar-mode is enabled?
>> 
>> I guess the users still need to decide whether they want to open
>> new tabs in the tab-bar (when eww-browse-url-new-window-is-tab is non-nil),
>> or new tabs in the tab-line (when eww-browse-url-new-window-is-tab is nil)
>> that just creates a new buffer displayed in the window-local tab-line -
>> this is the current behavior.
>> 
>> Another use case is that when tab-bar-mode is not yet enabled,
>> users migth prefer that clicking on a link with a Ctrl key
>> could enable the tab-bar and open a new tab in automatically
>> enabled tab-bar.
>
> It seems to me that there are sensible defaults in each of these
> situations, and we could use those defaults unconditionally until
> users complained.
>
> Adding too many user options has a downside as well, you know.
>
> Just one opinion.

I agree, let's try this heuristics to open new tabs
when tab-bar-mode is enabled:

diff --git a/doc/misc/eww.texi b/doc/misc/eww.texi
index b8821cbc29..d0a4c9a790 100644
--- a/doc/misc/eww.texi
+++ b/doc/misc/eww.texi
@@ -105,7 +105,10 @@ Basics
 @kindex M-RET
   The @kbd{M-@key{RET}} command (@code{eww-open-in-new-buffer}) opens the
 URL at point in a new EWW buffer, akin to opening a link in a new
-``tab'' in other browsers.
+``tab'' in other browsers.  When @code{global-tab-line-mode} is
+enabled, this buffer is displayed in the tab on the window tab line.
+When @code{tab-bar-mode} is enabled, a new tab is created on the frame
+tab bar.
 
 @findex eww-readable
 @kindex R
diff --git a/lisp/net/eww.el b/lisp/net/eww.el
index fb495a9858..0756c6088b 100644
--- a/lisp/net/eww.el
+++ b/lisp/net/eww.el
@@ -369,6 +369,9 @@ eww-open-in-new-buffer
   (interactive)
   (let ((url (eww-suggested-uris)))
     (if (null url) (user-error "No link at point")
+      (when tab-bar-mode
+        (let ((tab-bar-new-tab-choice t))
+          (tab-new)))
       ;; clone useful to keep history, but
       ;; should not clone from non-eww buffer
       (with-current-buffer
@@ -878,7 +881,22 @@ eww-mode
 
 ;;;###autoload
 (defun eww-browse-url (url &optional new-window)
+  "Ask the EWW browser to load URL.
+
+Interactively, if the variable `browse-url-new-window-flag' is non-nil,
+loads the document in a new buffer tab on the window tab-line.  A non-nil
+prefix argument reverses the effect of `browse-url-new-window-flag'.
+
+If `tab-bar-mode' is enabled, then whenever a document would
+otherwise be loaded in a new buffer, it is loaded in a new tab
+in the tab-bar on an existing frame.
+
+Non-interactively, this uses the optional second argument NEW-WINDOW
+instead of `browse-url-new-window-flag'."
   (when new-window
+    (when tab-bar-mode
+      (let ((tab-bar-new-tab-choice t))
+        (tab-new)))
     (pop-to-buffer-same-window
      (generate-new-buffer
       (format "*eww-%s*" (url-host (url-generic-parse-url
diff --git a/lisp/net/shr.el b/lisp/net/shr.el
index 628cc17a5b..f3d5de9fb6 100644
--- a/lisp/net/shr.el
+++ b/lisp/net/shr.el
@@ -201,6 +201,7 @@ shr-map
     (define-key map [?\M-\t] 'shr-previous-link)
     (define-key map [follow-link] 'mouse-face)
     (define-key map [mouse-2] 'shr-browse-url)
+    (define-key map [C-down-mouse-1] 'shr-mouse-browse-url-new-window)
     (define-key map "I" 'shr-insert-image)
     (define-key map "w" 'shr-maybe-probe-and-copy-url)
     (define-key map "u" 'shr-maybe-probe-and-copy-url)
@@ -967,7 +968,13 @@ shr-mouse-browse-url
   (mouse-set-point ev)
   (shr-browse-url))
 
-(defun shr-browse-url (&optional external mouse-event)
+(defun shr-mouse-browse-url-new-window (ev)
+  "Browse the URL under the mouse cursor in a new window."
+  (interactive "e")
+  (mouse-set-point ev)
+  (shr-browse-url nil nil t))
+
+(defun shr-browse-url (&optional external mouse-event new-window)
   "Browse the URL at point using `browse-url'.
 If EXTERNAL is non-nil (interactively, the prefix argument), browse
 the URL using `browse-url-secondary-browser-function'.
@@ -987,7 +994,9 @@ shr-browse-url
           (progn
            (funcall browse-url-secondary-browser-function url)
             (shr--blink-link))
-       (browse-url url))))))
+       (browse-url url (if new-window
+                           (not browse-url-new-window-flag)
+                         browse-url-new-window-flag)))))))
 
 (defun shr-save-contents (directory)
   "Save the contents from URL in a file."