[orca] Ignore events from sources whose state set is empty

[Joanmarie Diggs <joanied src gnome org>]

commit 3c44a50fd5b2211f9ff93a0646a8a62f9b4ebbb3
Author: Joanmarie Diggs <jdiggs igalia com>
Date:   Tue Apr 21 11:44:37 2020 -0400

    Ignore events from sources whose state set is empty
    
    When we go to process any event, we always look for relevant states and
    stop processing the event should the relevant states be missing. If the
    event comes from a source with an empty state set, there's no point in
    queueing it up for processing.

 src/orca/event_manager.py | 6 ++++++
 1 file changed, 6 insertions(+)
---
diff --git a/src/orca/event_manager.py b/src/orca/event_manager.py
index 7bdc57f08..d3e6f45a4 100644
--- a/src/orca/event_manager.py
+++ b/src/orca/event_manager.py
@@ -157,6 +157,12 @@ class EventManager:
             msg = 'ERROR: Event is from potentially-defunct source'
             debug.println(debug.LEVEL_INFO, msg, True)
             return True
+
+        if state.isEmpty():
+            msg = 'EVENT MANAGER: Ignoring event due to empty state set'
+            debug.println(debug.LEVEL_INFO, msg, True)
+            return True
+
         if state.contains(pyatspi.STATE_DEFUNCT):
             msg = 'ERROR: Event is from defunct source'
             debug.println(debug.LEVEL_INFO, msg, True)