[mousetrap/gnome3-wip] Fixed 709337 - Attribute Error in preferences menu. Check added to verify valid object before perfor

[Heidi Ellis <heidiellis src gnome org>]

commit f9acfbc502ac8134ac275008b6ecf075d635af79
Author: Logan Hotchkiss <lhotchkiss17 gmail com>
Date:   Thu Oct 17 20:40:16 2013 -0400

    Fixed 709337 - Attribute Error in preferences menu. Check added to verify valid object before performing 
operations.

 src/mousetrap/app/ui/settings_gui.py |   13 +++++++------
 1 files changed, 7 insertions(+), 6 deletions(-)
---
diff --git a/src/mousetrap/app/ui/settings_gui.py b/src/mousetrap/app/ui/settings_gui.py
index 2fdfe6c..001d911 100644
--- a/src/mousetrap/app/ui/settings_gui.py
+++ b/src/mousetrap/app/ui/settings_gui.py
@@ -485,12 +485,13 @@ class PreffGui( Gtk.Window ):
         """
 
         ts = widget.get_selection()
-        model, it = ts.get_selected()
-        path = model.get_path(it)[0]
-        if model[path][0] and model[path][3]:
-            self.selected_idm = model[path][1]
-            self.selected_idm_stgs = model[path][3]
-            conf_button.set_sensitive(True)
+        if(ts):
+            model, it = ts.get_selected()
+            path = model.get_path(it)[0]
+            if model[path][0] and model[path][3]:
+                self.selected_idm = model[path][1]
+                self.selected_idm_stgs = model[path][3]
+                conf_button.set_sensitive(True)
 
     def _toggle_cell_changed(self, cell, path, model):
         """