Improve documentation of p-s-p-scroll-down-page

* lisp/pixel-scroll.el
(pixel-scroll-precision-scroll-down-page): Document unit in
which the height of the window is measured, and what manner of
height applies.  Reported by Eli Zaretskii <eliz@gnu.org>.

(cherry picked from commit 1c4b1ce8fa7c752454c144d78d8ae14ee88150d3)

diff --git a/lisp/pixel-scroll.el b/lisp/pixel-scroll.el
index 20c7f3fe59608e1949a5262a3330cb6e90dcd7bd..1f963ee8114248b528bde2f71a3fcabb10550f6d 100644 (file)
--- a/lisp/pixel-scroll.el
+++ b/lisp/pixel-scroll.el
@@ -502,7 +502,7 @@ Otherwise, redisplay will reset the window's vscroll."
 (defun pixel-scroll-precision-scroll-down-page (delta)
   "Scroll the current window down by DELTA pixels.
 Note that this function doesn't work if DELTA is larger than or
-equal to the height of the current window."
+equal to the text height of the current window in pixels."
   (let* ((desired-pos (posn-at-x-y 0 (+ delta
                                        (window-tab-line-height)
                                        (window-header-line-height))))