Handle persistence of windows' scroll bar and fringes settings (Bug#36193)

* doc/lispref/display.texi (Fringe Size/Pos): Document new
argument PERSISTENT of 'set-window-fringes'.
(Scroll Bars): Document new argument PERSISTENT of
'set-window-scroll-bars'.  Mention that HORIZONTAL-TYPE must
be 'bottom' to show a horizontal scroll bar on mini windows.
* lisp/window.el (window-min-pixel-height): For mini windows the
minimum height is one line.
(window--min-size-1): Use value returned by
'window-min-pixel-height' when dealing with mini windows.
(window--resize-mini-window): Try to handle horizontal scroll
bars and size restrictions more accurately.
(window--state-put-2): Handle persistence of scroll bar
settings.
* src/frame.c (make_frame): Allow horizontal scroll bars in
mini windows.
(adjust_frame_size): Drop PIXELWISE argument in
'resize_frame_windows' calls.
* src/window.c (set_window_buffer): Don't override WINDOW's
scroll bar and fringe settings when marked as persistent.
(resize_frame_windows): Drop fourth argument PIXELWISE - SIZE
is always specified in terms of pixels.  Try to handle height
of mini windows more accurately.
(grow_mini_window, shrink_mini_window): Use body height of
mini window when calculating expected height change.  Take
horizontal scroll bars into account.
(struct saved_window): Two new members to handle persistence
of window fringes and scroll bars.
(Fset_window_configuration, save_window_save): Handle
persistence of fringes and scroll bars.
(set_window_fringes, set_window_scroll_bars): New arguments
PERSISTENT.  Make dimension checks more accurate.
(Fset_window_fringes): New argument PERSISTENT.
(Fwindow_fringes, Fwindow_scroll_bars): Add PERSISTENT to
return values.
(Fset_window_scroll_bars): New argument PERSISTENT.  In
doc-string mention that 'bottom' must be specified to get a
horizontal scroll bar in mini windows.
(compare_window_configurations): Add checks for persistence of
fringes and scroll bars.
* src/window.h (struct window): New boolean slots
'fringes_persistent' and 'scroll_bars_persistent'.
(WINDOW_HAS_HORIZONTAL_SCROLL_BAR): Allow horizontal scroll bars
for mini windows.
(resize_frame_windows): Remove fourth argument of
'resize_frame_windows' in external declaration.
* src/xdisp.c (resize_mini_window): Use box text height to
tell whether mini window height changed.
(set_horizontal_scroll_bar): Set mini window's horizontal
scroll bar when its type is specified as 'bottom'.
* etc/NEWS: Mention new options for 'set-window-fringes' and
'set-window-scroll-bars'.

1 files changed, 20 insertions, 19 deletions

diff --git a/lisp/window.el b/lisp/window.el
index 8cb9670ae47..8597f870a5b 100644
--- a/lisp/window.el
+++ b/lisp/window.el
@@ -434,7 +434,8 @@ shorter, explicitly specify the SIZE argument of that function."
 
 (defun window-min-pixel-height (&optional window)
   "Return the minimum pixel height of window WINDOW."
-  (* (max window-min-height window-safe-min-height)
+  (* (max (if (window-minibuffer-p window) 1 window-min-height)
+          window-safe-min-height)
      (frame-char-size window)))
 
 ;; This must go to C, finally (or get removed).
@@ -1603,8 +1604,6 @@ return the minimum pixel-size of WINDOW."
           value)
       (with-current-buffer (window-buffer window)
         (cond
-         ((window-minibuffer-p window)
-          (if pixelwise (frame-char-height (window-frame window)) 1))
          ((window-size-fixed-p window horizontal ignore)
           ;; The minimum size of a fixed size window is its size.
           (window-size window horizontal pixelwise))
@@ -2739,30 +2738,32 @@ windows."
   (when (window-right window)
     (window--resize-reset-1 (window-right window) horizontal)))
 
+;; The following is the internal function used when resizing mini
+;; windows "manually", for example, when dragging a divider between
+;; root and mini window.  The routines for automatic minibuffer window
+;; resizing call `window--resize-root-window-vertically' instead.
 (defun window--resize-mini-window (window delta)
-  "Resize minibuffer window WINDOW by DELTA pixels.
+  "Change height of mini window WINDOW by DELTA pixels.
 If WINDOW cannot be resized by DELTA pixels make it as large (or
 as small) as possible, but don't signal an error."
   (when (window-minibuffer-p window)
     (let* ((frame (window-frame window))
            (root (frame-root-window frame))
            (height (window-pixel-height window))
-           (min-delta
-            (- (window-pixel-height root)
-               (window-min-size root nil nil t))))
-      ;; Sanitize DELTA.
-      (cond
-       ((<= (+ height delta) 0)
-        (setq delta (- (frame-char-height frame) height)))
-       ((> delta min-delta)
-        (setq delta min-delta)))
+           (min-height (+ (frame-char-height frame)
+                          (- (window-pixel-height window)
+                             (window-body-height window t))))
+           (max-delta (- (window-pixel-height root)
+                         (window-min-size root nil nil t))))
+      ;; Don't make mini window too small.
+      (when (< (+ height delta) min-height)
+        (setq delta (- min-height height)))
+      ;; Don't make root window too small.
+      (when (> delta max-delta)
+        (setq delta max-delta))
 
       (unless (zerop delta)
-        ;; Resize now.
         (window--resize-reset frame)
-        ;; Ideally we should be able to resize just the last child of root
-        ;; here.  See the comment in `resize-root-window-vertically' for
-        ;; why we do not do that.
         (window--resize-this-window root (- delta) nil nil t)
         (set-window-new-pixel window (+ height delta))
         ;; The following routine catches the case where we want to resize
@@ -5881,7 +5882,7 @@ value can be also stored on disk and read back in a new session."
                 (let ((scroll-bars (cdr (assq 'scroll-bars state))))
                   (set-window-scroll-bars
                    window (car scroll-bars) (nth 2 scroll-bars)
-                   (nth 3 scroll-bars) (nth 5 scroll-bars)))
+                   (nth 3 scroll-bars) (nth 5 scroll-bars) (nth 6 scroll-bars)))
                 (set-window-vscroll window (cdr (assq 'vscroll state)))
                 ;; Adjust vertically.
                 (if (or (memq window-size-fixed '(t height))
@@ -8497,7 +8498,7 @@ parameters of FRAME."
             (if parent
                 (frame-native-height parent)
               (- (nth 3 geometry) (nth 1 geometry))))
-           ;; FRAME'S parent or workarea sizes.  Used when no margins
+           ;; FRAME's parent or workarea sizes.  Used when no margins
            ;; are specified.
            (parent-or-workarea
             (if parent