[gimp] app: don't ignore return value

[Nils Philippsen <nphilipp src gnome org>]

commit 391de600f1bd76aa21a3ec1ea4d349ef04cc160b
Author: Nils Philippsen <nils redhat com>
Date:   Thu Nov 7 12:28:28 2013 +0100

    app: don't ignore return value
    
    ...of gtk_widget_translate_coordinates()

 app/widgets/gimpdeviceinfo-coords.c |   12 +++++++-----
 1 files changed, 7 insertions(+), 5 deletions(-)
---
diff --git a/app/widgets/gimpdeviceinfo-coords.c b/app/widgets/gimpdeviceinfo-coords.c
index d974af2..9fef657 100644
--- a/app/widgets/gimpdeviceinfo-coords.c
+++ b/app/widgets/gimpdeviceinfo-coords.c
@@ -63,11 +63,13 @@ gimp_device_info_get_event_coords (GimpDeviceInfo *info,
               gint offset_x;
               gint offset_y;
 
-              gtk_widget_translate_coordinates (src_widget, dest_widget,
-                                                0, 0, &offset_x, &offset_y);
-
-              coords->x += offset_x;
-              coords->y += offset_y;
+              if (gtk_widget_translate_coordinates (src_widget, dest_widget,
+                                                    0, 0,
+                                                    &offset_x, &offset_y))
+                {
+                  coords->x += offset_x;
+                  coords->y += offset_y;
+                }
             }
         }