Fix indexing of mouse-wheel events

* doc/emacs/frames.texi (Mouse Commands): Add index entries for
wheel events.

1 files changed, 9 insertions, 1 deletions

diff --git a/doc/emacs/frames.texi b/doc/emacs/frames.texi
index d78cbffaa71..93a6cd70d3f 100644
--- a/doc/emacs/frames.texi
+++ b/doc/emacs/frames.texi
@@ -215,6 +215,10 @@ deactivating the mark.  @xref{Shift Selection}.
 @vindex mouse-wheel-follow-mouse
 @vindex mouse-wheel-scroll-amount
 @vindex mouse-wheel-progressive-speed
+@cindex wheel-up, a mouse event
+@cindex wheel-down, a mouse event
+@cindex wheel-left, a mouse event
+@cindex wheel-right, a mouse event
   Some mice have a ``wheel'' which can be used for scrolling.  Emacs
 supports scrolling windows with the mouse wheel, by default, on most
 graphical displays.  To toggle this feature, use @kbd{M-x
@@ -224,7 +228,11 @@ buffers are scrolled.  The variable
 @code{mouse-wheel-progressive-speed} determines whether the scroll
 speed is linked to how fast you move the wheel.  This mode also
 supports increasing or decreasing the font size, by default bound to
-scrolling with the @key{Ctrl} modifier.
+scrolling with the @key{Ctrl} modifier.  When this mode is enabled,
+mouse wheel produces special events like @code{wheel-up} and
+@code{wheel-down}.  (Some older systems report them as @code{mouse-4}
+and @code{mouse-5}.)  If the mouse has a horizontal scroll wheel, it
+produces @code{wheel-left} and @code{wheel-right} events as well..
 
 @vindex mouse-wheel-scroll-amount-horizontal
 Emacs also supports horizontal scrolling with the @key{Shift}