year-view: don't render DnD when it leaves

data/ui/year-view.ui

@@ -26,6 +26,7 @@
                 <signal name="motion-notify-event" handler="navigator_motion_notify_cb" object="GcalYearView" swapped="yes"/>
                 <signal name="drag-motion" handler="navigator_drag_motion_cb" object="GcalYearView" swapped="yes"/>
                 <signal name="drag-drop" handler="navigator_drag_drop_cb" object="GcalYearView" swapped="yes"/>
+                <signal name="drag-leave" handler="navigator_drag_leave_cb" object="GcalYearView" swapped="yes"/>
                 <style>
                   <class name="year-navigator"/>
                 </style>

src/gcal-year-view.c

@@ -1375,6 +1375,19 @@ navigator_drag_drop_cb (GcalYearView   *self,
   return TRUE;
 }
 
+static void
+navigator_drag_leave_cb (GcalYearView   *self,
+                         GdkDragContext *context,
+                         guint           time,
+                         GtkWidget      *navigator)
+{
+  /* Cancel the DnD after the event is dropped */
+  self->selected_data->dnd_day = -1;
+  self->selected_data->dnd_month = -1;
+
+  gtk_widget_queue_draw (navigator);
+}
+
 static void
 gcal_year_view_finalize (GObject *object)
 {
@@ -1770,6 +1783,7 @@ gcal_year_view_class_init (GcalYearViewClass *klass)
   gtk_widget_class_bind_template_callback (widget_class, navigator_button_press_cb);
   gtk_widget_class_bind_template_callback (widget_class, navigator_button_release_cb);
   gtk_widget_class_bind_template_callback (widget_class, navigator_drag_drop_cb);
+  gtk_widget_class_bind_template_callback (widget_class, navigator_drag_leave_cb);
   gtk_widget_class_bind_template_callback (widget_class, navigator_drag_motion_cb);
   gtk_widget_class_bind_template_callback (widget_class, navigator_motion_notify_cb);
   gtk_widget_class_bind_template_callback (widget_class, add_event_clicked_cb);