Fix interaction of line-dragging with mouse-1-click-follows-link.

* lisp/mouse.el (mouse-drag-line): Rewrite the track-mouse loop.
Implement the mouse-1-click-follows-link handling properly.

* lisp/info.el (Info-link-keymap): Use follow-link mechanism for
header-line links.

Fixes: debbugs:374

3 files changed, 67 insertions, 99 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 8a608ea7b10..dbe37763d7a 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,5 +1,11 @@
 2012-07-08  Chong Yidong  <cyd@gnu.org>
 
+        * mouse.el (mouse-drag-line): Rewrite the track-mouse loop.
+        Implement the mouse-1-click-follows-link handling properly.
+
+        * info.el (Info-link-keymap): Use follow-link mechanism for
+        header-line links (Bug#374).
+
         * simple.el (deactivate-mark): Do not set the primary selection
         if another program has acquired it (Bug#11772).
 
diff --git a/lisp/info.el b/lisp/info.el
index 9a62bc23fd0..0afb3f01339 100644
--- a/lisp/info.el
+++ b/lisp/info.el
@@ -4361,9 +4361,9 @@ the variable `Info-file-list-for-emacs'."
 
 (defvar Info-link-keymap
   (let ((keymap (make-sparse-keymap)))
-    (define-key keymap [header-line mouse-1] 'Info-mouse-follow-link)
+    (define-key keymap [header-line down-mouse-1] 'mouse-drag-header-line)
+    (define-key keymap [header-line mouse-1] 'mouse-select-window)
     (define-key keymap [header-line mouse-2] 'Info-mouse-follow-link)
-    (define-key keymap [header-line down-mouse-1] 'ignore)
     (define-key keymap [mouse-2] 'Info-mouse-follow-link)
     (define-key keymap [follow-link] 'mouse-face)
     keymap)
diff --git a/lisp/mouse.el b/lisp/mouse.el
index c130a27a8e4..a0d10a64945 100644
--- a/lisp/mouse.el
+++ b/lisp/mouse.el
@@ -388,10 +388,11 @@ This command must be bound to a mouse click."
 
 ;; Note that `window-in-direction' replaces `mouse-drag-window-above'
 ;; and `mouse-drag-vertical-line-rightward-window' with Emacs 24.1.
+
 (defun mouse-drag-line (start-event line)
-  "Drag some line with the mouse.
+  "Drag a mode line, header line, or vertical line with the mouse.
 START-EVENT is the starting mouse-event of the drag action.  LINE
-must be one of the symbols header, mode, or vertical."
+must be one of the symbols `header', `mode', or `vertical'."
   ;; Give temporary modes such as isearch a chance to turn off.
   (run-hooks 'mouse-leave-buffer-hook)
   (let* ((echo-keystrokes 0)
@@ -400,122 +401,85 @@ must be one of the symbols header, mode, or vertical."
          (frame (window-frame window))
          (minibuffer-window (minibuffer-window frame))
          (on-link (and mouse-1-click-follows-link
-                       (or mouse-1-click-in-non-selected-windows
-                           (eq window (selected-window)))
                        (mouse-on-link-p start)))
-         (resize-minibuffer
-          ;; Resize the minibuffer window if it's on the same frame as
-          ;; and immediately below the position window and it's either
-          ;; active or `resize-mini-windows' is nil.
-          (and (eq line 'mode)
-               (eq (window-frame minibuffer-window) frame)
-               (= (nth 1 (window-edges minibuffer-window))
-                  (nth 3 (window-edges window)))
-               (or (not resize-mini-windows)
-                   (eq minibuffer-window (active-minibuffer-window)))))
-         (which-side
-          (and (eq line 'vertical)
-               (or (cdr (assq 'vertical-scroll-bars (frame-parameters frame)))
-                   'right)))
-         done event mouse growth dragged)
+         (side (and (eq line 'vertical)
+                    (or (cdr (assq 'vertical-scroll-bars
+                                   (frame-parameters frame)))
+                        'right)))
+         (draggable t)
+         event position growth dragged)
     (cond
      ((eq line 'header)
       ;; Check whether header-line can be dragged at all.
       (if (window-at-side-p window 'top)
-          (setq done t)
+          (setq draggable nil)
         (setq window (window-in-direction 'above window t))))
      ((eq line 'mode)
       ;; Check whether mode-line can be dragged at all.
-      (when (and (window-at-side-p window 'bottom)
-                 (not resize-minibuffer))
-        (setq done t)))
+      (and (window-at-side-p window 'bottom)
+           ;; Allow resizing the minibuffer window if it's on the same
+           ;; frame as and immediately below the clicked window, and
+           ;; it's active or `resize-mini-windows' is nil.
+           (not (and (eq (window-frame minibuffer-window) frame)
+                     (= (nth 1 (window-edges minibuffer-window))
+                        (nth 3 (window-edges window)))
+                     (or (not resize-mini-windows)
+                         (eq minibuffer-window
+                             (active-minibuffer-window)))))
+           (setq draggable nil)))
      ((eq line 'vertical)
-      ;; Get the window to adjust for the vertical case.
-      (setq window
-            (if (eq which-side 'right)
-                ;; If the scroll bar is on the window's right or there's
-                ;; no scroll bar at all, adjust the window where the
-                ;; start-event occurred.
-                window
-              ;; If the scroll bar is on the start-event window's left,
-              ;; adjust the window on the left of it.
-              (window-in-direction 'left window t)))))
+      ;; Get the window to adjust for the vertical case.  If the
+      ;; scroll bar is on the window's right or there's no scroll bar
+      ;; at all, adjust the window where the start-event occurred.  If
+      ;; the scroll bar is on the start-event window's left, adjust
+      ;; the window on the left of it.
+      (unless (eq side 'right)
+        (setq window (window-in-direction 'left window t)))))
 
     ;; Start tracking.
     (track-mouse
-      ;; Loop reading events and sampling the position of the mouse.
-      (while (not done)
-        (setq event (read-event))
-        (setq mouse (mouse-position))
-        ;; Do nothing if
-        ;;   - there is a switch-frame event.
-        ;;   - the mouse isn't in the frame that we started in
-        ;;   - the mouse isn't in any Emacs frame
-        ;; Drag if
-        ;;   - there is a mouse-movement event
-        ;;   - there is a scroll-bar-movement event (??)
-        ;;     (same as mouse movement for our purposes)
-        ;; Quit if
-        ;;   - there is a keyboard event or some other unknown event.
+      ;; Loop reading events and sampling the position of the mouse,
+      ;; until there is a non-mouse-movement event.  Also,
+      ;; scroll-bar-movement events are the same as mouse movement for
+      ;; our purposes.  (Why? -- cyd)
+      (while (progn
+               (setq event (read-event))
+               (memq (car-safe event) '(mouse-movement scroll-bar-movement)))
+        (setq position (mouse-position))
         (cond
-         ((not (consp event))
-          (setq done t))
-         ((memq (car event) '(switch-frame select-window))
-          nil)
-         ((not (memq (car event) '(mouse-movement scroll-bar-movement)))
-          (when (consp event)
-            ;; Do not unread a drag-mouse-1 event to avoid selecting
-            ;; some other window.  For vertical line dragging do not
-            ;; unread mouse-1 events either (but only if we dragged at
-            ;; least once to allow mouse-1 clicks get through.
-            (unless (and dragged
-                         (if (eq line 'vertical)
-                             (memq (car event) '(drag-mouse-1 mouse-1))
-                           (eq (car event) 'drag-mouse-1)))
-              (push event unread-command-events)))
-          (setq done t))
-         ((or (not (eq (car mouse) frame)) (null (car (cdr mouse))))
+         ((or (not (eq (car position) frame))
+              (null (cadr position)))
           nil)
          ((eq line 'vertical)
-          ;; Drag vertical divider (the calculations below are those
-          ;; from Emacs 23).
-          (setq growth
-                (- (- (cadr mouse)
-                      (if (eq which-side 'right) 0 2))
-                   (nth 2 (window-edges window))
-                   -1))
+          ;; Drag vertical divider.
+          (setq growth (- (cadr position)
+                          (if (eq side 'right) 0 2)
+                          (nth 2 (window-edges window))
+                          -1))
           (unless (zerop growth)
-            ;; Remember that we dragged.
             (setq dragged t))
           (adjust-window-trailing-edge window growth t))
-         (t
-          ;; Drag horizontal divider (the calculations below are those
-          ;; from Emacs 23).
+         (draggable
+          ;; Drag horizontal divider.
           (setq growth
                 (if (eq line 'mode)
-                    (- (cddr mouse) (nth 3 (window-edges window)) -1)
+                    (- (cddr position) (nth 3 (window-edges window)) -1)
                   ;; The window's top includes the header line!
-                  (- (nth 3 (window-edges window)) (cddr mouse))))
-
+                  (- (nth 3 (window-edges window)) (cddr position))))
           (unless (zerop growth)
-            ;; Remember that we dragged.
             (setq dragged t))
+          (adjust-window-trailing-edge window (if (eq line 'mode)
+                                                  growth
+                                                (- growth)))))))
+    ;; Process the terminating event.
+    (when (and (mouse-event-p event) on-link (not dragged)
+               (mouse--remap-link-click-p start-event event))
+      ;; If mouse-2 has never been done by the user, it doesn't have
+      ;; the necessary property to be interpreted correctly.
+      (put 'mouse-2 'event-kind 'mouse-click)
+      (setcar event 'mouse-2))
+    (push event unread-command-events)))
 
-          (if (eq line 'mode)
-              (adjust-window-trailing-edge window growth)
-            (adjust-window-trailing-edge window (- growth))))))
-
-      ;; Presumably, if this was just a click, the last event should be
-      ;; `mouse-1', whereas if this did move the mouse, it should be a
-      ;; `drag-mouse-1'.  `dragged' nil tells us that we never dragged
-      ;; and `on-link' tells us that there is a link to follow.
-      (when (and on-link (not dragged)
-                 (eq 'mouse-1 (car-safe (car unread-command-events))))
-        ;; If mouse-2 has never been done by the user, it doesn't
-        ;; have the necessary property to be interpreted correctly.
-        (put 'mouse-2 'event-kind 'mouse-click)
-        (setcar unread-command-events
-                (cons 'mouse-2 (cdar unread-command-events)))))))
 
 (defun mouse-drag-mode-line (start-event)
   "Change the height of a window by dragging on the mode line."
@@ -791,10 +755,8 @@ DO-MOUSE-DRAG-REGION-POST-PROCESS should only be used by
                    ;; Don't count the mode line.
                    (1- (nth 3 bounds))))
          (on-link (and mouse-1-click-follows-link
-                       (or mouse-1-click-in-non-selected-windows
-                           (eq start-window original-window))
                        ;; Use start-point before the intangibility
-                       ;; treatment, in case we click on a link inside an
+                       ;; treatment, in case we click on a link inside
                        ;; intangible text.
                        (mouse-on-link-p start-posn)))
          (click-count (1- (event-click-count start-event)))