[gtk+] gtkmenu: ignore emulated scroll events

[Olivier Fourdan <ofourdan src gnome org>]

commit c134d52dd789d2f8b43e15e51fa72d9586a151ec
Author: Olivier Fourdan <ofourdan redhat com>
Date:   Tue May 3 16:44:14 2016 +0200

    gtkmenu: ignore emulated scroll events
    
    On X11, we get both smooth and emulated scroll events, whereas other
    backends such as wayland will give smooth events only with touchpad
    scrolling.
    
    Discard emulated scroll events so that we get consistent behaviours
    between backends.
    
    Allow for both horizontal and vertical smooth events for scrolling so
    that horizontal scrolling still works without emulated scroll events as
    well, again for consistency between gdk backends.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=765939

 gtk/gtkmenu.c |    7 ++++++-
 1 files changed, 6 insertions(+), 1 deletions(-)
---
diff --git a/gtk/gtkmenu.c b/gtk/gtkmenu.c
index c4c8431..ee24b72 100644
--- a/gtk/gtkmenu.c
+++ b/gtk/gtkmenu.c
@@ -105,6 +105,8 @@
 
 #include  <gobject/gvaluecollector.h>
 
+#include <gdk/gdkprivate.h> /* for _gdk_event_get_pointer_emulated() */
+
 #include "gtkaccellabel.h"
 #include "gtkaccelmap.h"
 #include "gtkadjustment.h"
@@ -3554,6 +3556,9 @@ gtk_menu_scroll (GtkWidget      *widget,
 {
   GtkMenu *menu = GTK_MENU (widget);
 
+  if (_gdk_event_get_pointer_emulated ((GdkEvent *) event))
+    return FALSE;
+
   switch (event->direction)
     {
     case GDK_SCROLL_RIGHT:
@@ -3565,7 +3570,7 @@ gtk_menu_scroll (GtkWidget      *widget,
       gtk_menu_scroll_by (menu, - MENU_SCROLL_STEP2);
       break;
     case GDK_SCROLL_SMOOTH:
-      gtk_menu_scroll_by (menu, event->delta_y);
+      gtk_menu_scroll_by (menu, event->delta_y * MENU_SCROLL_STEP2);
       break;
     }