Merge 'master' into noverlay

1 files changed, 24 insertions, 21 deletions

diff --git a/lisp/scroll-bar.el b/lisp/scroll-bar.el
index 8f02f2f3e9d..5786a21e88e 100644
--- a/lisp/scroll-bar.el
+++ b/lisp/scroll-bar.el
@@ -1,6 +1,6 @@
-;;; scroll-bar.el --- window system-independent scroll bar support
+;;; scroll-bar.el --- window system-independent scroll bar support  -*- lexical-binding: t; -*-
 
-;; Copyright (C) 1993-1995, 1999-2017 Free Software Foundation, Inc.
+;; Copyright (C) 1993-1995, 1999-2022 Free Software Foundation, Inc.
 
 ;; Maintainer: emacs-devel@gnu.org
 ;; Keywords: hardware
@@ -49,9 +49,7 @@ from a scroll bar event, then (scroll-bar-scale SCROLL-BAR-POS
 \(buffer-size)) is the position in the current buffer corresponding to
 that scroll bar position."
   ;; We multiply before we divide to maintain precision.
-  ;; We use floating point because the product of a large buffer size
-  ;; with a large scroll bar portion can easily overflow a lisp int.
-  (truncate (/ (* (float (car num-denom)) whole) (cdr num-denom))))
+  (truncate (* (car num-denom) whole) (cdr num-denom)))
 
 (defun scroll-bar-columns (side)
   "Return the width, measured in columns, of the vertical scrollbar on SIDE.
@@ -133,12 +131,12 @@ Setting the variable with a customization buffer also takes effect."
 
 (define-minor-mode scroll-bar-mode
   "Toggle vertical scroll bars on all frames (Scroll Bar mode).
-With a prefix argument ARG, enable Scroll Bar mode if ARG is
-positive, and disable it otherwise.  If called from Lisp, enable
-the mode if ARG is omitted or nil.
 
-This command applies to all frames that exist and frames to be
-created in the future."
+This command applies to all frames that exist, as well as new
+frames to be created in the future.  This is done by altering the
+frame parameters, so if you (re-)set `default-frame-alist' after
+toggling the scroll bars on or off with this command, the scroll
+bars may reappear on new frames."
   :variable ((get-scroll-bar-mode)
              . (lambda (v) (set-scroll-bar-mode
 			    (if v (or previous-scroll-bar-mode
@@ -152,9 +150,6 @@ created in the future."
 
 (define-minor-mode horizontal-scroll-bar-mode
   "Toggle horizontal scroll bars on all frames (Horizontal Scroll Bar mode).
-With a prefix argument ARG, enable Horizontal Scroll Bar mode if
-ARG is positive, and disable it otherwise.  If called from Lisp,
-enable the mode if ARG is omitted or nil.
 
 This command applies to all frames that exist and frames to be
 created in the future."
@@ -260,14 +255,22 @@ EVENT should be a scroll bar click or drag event."
   (let* ((start-position (event-start event))
 	 (window (nth 0 start-position))
 	 (portion-whole (nth 2 start-position)))
-    (save-excursion
-      (with-current-buffer (window-buffer window)
-	;; Calculate position relative to the accessible part of the buffer.
-	(goto-char (+ (point-min)
-		      (scroll-bar-scale portion-whole
-					(- (point-max) (point-min)))))
-	(vertical-motion 0 window)
-	(set-window-start window (point))))))
+    ;; With 'scroll-bar-adjust-thumb-portion' nil and 'portion-whole'
+    ;; indicating that the buffer is fully visible, do not scroll the
+    ;; window since that might make it impossible to scroll it back
+    ;; with GTK's thumb (Bug#32002).
+    (when (or scroll-bar-adjust-thumb-portion
+              (not (numberp (car portion-whole)))
+              (not (numberp (cdr portion-whole)))
+              (/= (car portion-whole) (cdr portion-whole)))
+      (save-excursion
+        (with-current-buffer (window-buffer window)
+	  ;; Calculate position relative to the accessible part of the buffer.
+	  (goto-char (+ (point-min)
+		        (scroll-bar-scale portion-whole
+					  (- (point-max) (point-min)))))
+	  (vertical-motion 0 window)
+	  (set-window-start window (point)))))))
 
 (defun scroll-bar-drag (event)
   "Scroll the window by dragging the scroll bar slider.