[orca] Sanity check to address the traceback reported in bgo#608319.

[Joanmarie Diggs <joanied src gnome org>]

commit 74aed1eef53b7861edea55ff8ffefeb7bcdb298b
Author: Joanmarie Diggs <joanmarie diggs gmail com>
Date:   Sat Jan 30 17:39:29 2010 -0500

    Sanity check to address the traceback reported in bgo#608319.

 src/orca/scripts/toolkits/Gecko/script.py |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)
---
diff --git a/src/orca/scripts/toolkits/Gecko/script.py b/src/orca/scripts/toolkits/Gecko/script.py
index f4846e9..7fe92bf 100644
--- a/src/orca/scripts/toolkits/Gecko/script.py
+++ b/src/orca/scripts/toolkits/Gecko/script.py
@@ -1454,7 +1454,8 @@ class Script(default.Script):
            and self.isSameObject(obj, event.source):
             return
 
-        if isinstance(orca_state.lastInputEvent, input_event.KeyboardEvent):
+        if isinstance(orca_state.lastInputEvent, input_event.KeyboardEvent) \
+           and orca_state.lastNonModifierKeyEvent:
             string = orca_state.lastNonModifierKeyEvent.event_string
             if self.useCaretNavigationModel(orca_state.lastInputEvent):
                 # Orca is set to control the caret and is in a place where