[gtk+] spinbutton: Update to using GdkEvent API

[Carlos Garnacho <carlosg src gnome org>]

commit e2eb20208b2ed9803f9eae4d51242d2455645f00
Author: Carlos Garnacho <carlosg gnome org>
Date:   Fri Aug 25 16:55:22 2017 +0200

    spinbutton: Update to using GdkEvent API

 gtk/gtkspinbutton.c |    8 ++++++--
 1 files changed, 6 insertions(+), 2 deletions(-)
---
diff --git a/gtk/gtkspinbutton.c b/gtk/gtkspinbutton.c
index 8952465..11c514c 100644
--- a/gtk/gtkspinbutton.c
+++ b/gtk/gtkspinbutton.c
@@ -1115,14 +1115,18 @@ gtk_spin_button_scroll (GtkWidget      *widget,
 {
   GtkSpinButton *spin = GTK_SPIN_BUTTON (widget);
   GtkSpinButtonPrivate *priv = spin->priv;
+  GdkScrollDirection direction;
 
-  if (event->direction == GDK_SCROLL_UP)
+  if (!gdk_event_get_scroll_direction ((GdkEvent *) event, &direction))
+    return GDK_EVENT_PROPAGATE;
+
+  if (direction == GDK_SCROLL_UP)
     {
       if (!gtk_widget_has_focus (widget))
         gtk_widget_grab_focus (widget);
       gtk_spin_button_real_spin (spin, gtk_adjustment_get_step_increment (priv->adjustment));
     }
-  else if (event->direction == GDK_SCROLL_DOWN)
+  else if (direction == GDK_SCROLL_DOWN)
     {
       if (!gtk_widget_has_focus (widget))
         gtk_widget_grab_focus (widget);