(mouse-drag-track): Suppress automatic hscrolling for initial down

event.

lisp/mouse.el

@@ -925,7 +925,11 @@ should only be used by mouse-drag-region."
 	 (click-count (1- (event-click-count start-event)))
 	 (remap-double-click (and on-link
 				  (eq mouse-1-click-follows-link 'double)
-				  (= click-count 1))))
+				  (= click-count 1)))
+	 ;; Suppress automatic hscrolling, because that is a nuisance
+	 ;; when setting point near the right fringe (but see below).
+	 (automatic-hscrolling-saved automatic-hscrolling)
+	 (automatic-hscrolling nil))
     (setq mouse-selection-click-count click-count)
     ;; In case the down click is in the middle of some intangible text,
     ;; use the end of that text, and put it in START-POINT.
@@ -946,6 +950,11 @@ should only be used by mouse-drag-region."
                      (memq (car-safe event) '(switch-frame select-window))))
           (if (memq (car-safe event) '(switch-frame select-window))
 	      nil
+	    ;; Automatic hscrolling did not occur during the call to
+	    ;; `read-event'; but if the user subsequently drags the
+	    ;; mouse, go ahead and hscroll.
+	    (let ((automatic-hscrolling automatic-hscrolling-saved))
+	      (redisplay))
 	    (setq end (event-end event)
 		  end-point (posn-point end))
 	    (if (numberp end-point)