Add documentation for horizontal scroll bars and fix some minor issues.

* buffer.c (scroll_bar_width, scroll_bar_height): Fix
doc-strings.
* window.c (Fset_window_scroll_bars): Fix doc-string.
(Fwindow_scroll_bars): Have it return what the doc-string says.

* window.el (window-full-height-p): Make it behave correctly for
minibuffer window.
(window-current-scroll-bars): Fix code.
(fit-frame-to-buffer): Use window-scroll-bar-height instead of
window-scroll-bars.
* frame.el (frame-current-scroll-bars): Fix doc-string.
* scroll-bar.el (toggle-horizontal-scroll-bar): New command.

* frames.texi (Scroll Bars): Describe use of horizontal scroll
bars.

* display.texi (Scroll Bars): Add description of horizontal scroll
bars and associated functions.
* frames.texi (Layout Parameters): Add horizontal scroll bar
entries.  Remove paragraph on "combined fringe widths".
* windows.texi (Window Sizes): Describe affects of horizontal
scroll bars on window layout and sizes.  Fix description of
window-full-height-p.
(Resizing Windows): Mention horizontal scroll bar.

1 files changed, 19 insertions, 13 deletions

diff --git a/src/window.c b/src/window.c
index 456a8bce691..0b0f2140a58 100644
--- a/src/window.c
+++ b/src/window.c
@@ -7002,16 +7002,17 @@ DEFUN ("set-window-scroll-bars", Fset_window_scroll_bars,
        doc: /* Set width and type of scroll bars of window WINDOW.
 WINDOW must be a live window and defaults to the selected one.
 
-Second parameter WIDTH specifies the pixel width for the scroll bar.
+Second parameter WIDTH specifies the pixel width for the vertical scroll
+bar.  If WIDTH is nil, use the scroll-bar width of WINDOW's frame.
 Third parameter VERTICAL-TYPE specifies the type of the vertical scroll
-bar: left, right, or nil.  If WIDTH is nil, use the frame's scroll-bar
-width.  If VERTICAL-TYPE is t, use the frame's scroll-bar type.
+bar: left, right, or nil.  If VERTICAL-TYPE is t, this means use the
+frame's scroll-bar type.
 
-Fourth parameter HEIGHT specifies the pixel height for the scroll bar.
-Fifth parameter HORIZONTAL-TYPE specifies the type of the vertical
-scroll bar: nil, bottom, or t.  If HEIGHT is nil, use the frame's
-scroll-bar height.  If HORIZONTAL-TYPE is t, use the frame's scroll-bar
-type.
+Fourth parameter HEIGHT specifies the pixel height for the horizontal
+scroll bar.  If HEIGHT is nil, use the scroll-bar height of WINDOW's
+frame.  Fifth parameter HORIZONTAL-TYPE specifies the type of the
+horizontal scroll bar: nil, bottom, or t.  If HORIZONTAL-TYPE is t, this
+means to use the frame's horizontal scroll-bar type.
 
 Return t if scroll bars were actually changed and nil otherwise.  */)
   (Lisp_Object window, Lisp_Object width, Lisp_Object vertical_type,
@@ -7029,17 +7030,22 @@ DEFUN ("window-scroll-bars", Fwindow_scroll_bars, Swindow_scroll_bars,
        doc: /* Get width and type of scroll bars of window WINDOW.
 WINDOW must be a live window and defaults to the selected one.
 
-Value is a list of the form (WIDTH COLS VERTICAL-TYPE HEIGHT LINES
-HORIZONTAL-TYPE).  If WIDTH or HEIGHT is nil or TYPE is t, the window is
-using the frame's corresponding value.  */)
+Value is a list of the form (WIDTH COLUMNS VERTICAL-TYPE HEIGHT LINES
+HORIZONTAL-TYPE).  If WIDTH or HEIGHT is nil or VERTICAL-TYPE or
+HORIZONTAL-TYPE is t, the window is using the frame's corresponding
+value.  */)
   (Lisp_Object window)
 {
   struct window *w = decode_live_window (window);
 
-  return Fcons (make_number (WINDOW_SCROLL_BAR_AREA_WIDTH (w)),
+  return Fcons (((w->scroll_bar_width >= 0)
+                 ? make_number (w->scroll_bar_width)
+                 : Qnil),
                 list5 (make_number (WINDOW_SCROLL_BAR_COLS (w)),
                        w->vertical_scroll_bar_type,
-                       make_number (WINDOW_SCROLL_BAR_AREA_HEIGHT (w)),
+                       ((w->scroll_bar_height >= 0)
+                        ? make_number (w->scroll_bar_height)
+                        : Qnil),
                        make_number (WINDOW_SCROLL_BAR_LINES (w)),
                        w->horizontal_scroll_bar_type));
 }