Support precision mouse scrolling on MS-Windows

* src/w32fns.c (w32_wnd_proc): Pass the WM_SETTINGCHANGE message
to the Lisp thread.
* src/w32term.c (w32_construct_mouse_wheel): Support mice with
precision scrolling wheel.
(w32_get_mouse_wheel_vertical_delta): New function.
(w32_read_socket): When the WM_SETTINGCHANGE is received, call
'w32_get_mouse_wheel_vertical_delta'.
(w32_initialize): Call 'w32_get_mouse_wheel_vertical_delta' at
startup.
* src/nsterm.m (syms_of_nsterm):
* src/haikuterm.c (syms_of_haikuterm):
* src/xterm.c (syms_of_xterm): Remove window-system specific
variables for coalescing mwheel events.
* src/keyboard.c (syms_of_keyboard)
<mwheel-coalesce-scroll-events>: New variable, to replace the
above platform-specific ones.

* doc/lispref/commands.texi (Misc Events): Improve wording of the
description of mouse-wheel events.

1 files changed, 7 insertions, 0 deletions

diff --git a/src/w32fns.c b/src/w32fns.c
index c1686beaaa9..65463b52616 100644
--- a/src/w32fns.c
+++ b/src/w32fns.c
@@ -5173,6 +5173,13 @@ w32_wnd_proc (HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
       my_post_msg (&wmsg, hwnd, msg, wParam, lParam);
       goto dflt;
 
+    case WM_SETTINGCHANGE:
+      /* Inform the Lisp thread that some system-wide setting has
+	 changed, so if Emacs is interested in some of them, it could
+	 update its internal values.  */
+      my_post_msg (&wmsg, hwnd, msg, wParam, lParam);
+      goto dflt;
+
     case WM_SETFOCUS:
       dpyinfo->faked_key = 0;
       reset_modifiers ();