[gtk+] widget: Ignore non-gestures in _gtk_widget_consumes_motion

[Timm Bäder <baedert src gnome org>]

commit a89e88fc3ec55b5d4fc65e2d59b391b515a72974
Author: Timm Bäder <mail baedert org>
Date:   Thu Jan 4 13:15:15 2018 +0100

    widget: Ignore non-gestures in _gtk_widget_consumes_motion
    
    priv->event_controllers is a list of all event controllers, which aren't
    all GtkGesture subclasses.

 gtk/gtkwidget.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)
---
diff --git a/gtk/gtkwidget.c b/gtk/gtkwidget.c
index e61ef97..02e651a 100644
--- a/gtk/gtkwidget.c
+++ b/gtk/gtkwidget.c
@@ -14488,7 +14488,8 @@ _gtk_widget_consumes_motion (GtkWidget        *widget,
     {
       data = l->data;
 
-      if (data->controller == NULL)
+      if (data->controller == NULL ||
+          !GTK_IS_GESTURE (data->controller))
         continue;
 
       if ((!GTK_IS_GESTURE_SINGLE (data->controller) ||