Fix aziz#147 (ignore DirModifiedEvent)

this event seems useful only for monitoring the time changes, mostly
time of access, which is pointless in the particular case, and ignoring
it should significantly reduce excessive refresh calls

0_dired_fs_observer.py

@@ -24,7 +24,7 @@
 try:  # unavailable dependencies shall not break basic functionality
     import package_events
     from watchdog.observers import Observer
-    from watchdog.events import FileSystemEventHandler
+    from watchdog.events import FileSystemEventHandler, DirModifiedEvent
 except ImportError:
     Observer = None
     FileSystemEventHandler = object
@@ -167,6 +167,19 @@ def on_any_event(self, event):
         not to be confused with package_events which we use for internal communication
         dir(event) = ['event_type', 'is_directory', 'key', 'src_path']
         '''
+        if isinstance(event, DirModifiedEvent):
+            # change of access time may cause modified event, which can be safely ignored
+            # actual changes will fire the corresponding event types:
+            # FileMovedEvent
+            # DirMovedEvent
+            # FileModifiedEvent
+            # FileCreatedEvent
+            # DirCreatedEvent
+            # FileDeletedEvent
+            # DirDeletedEvent
+            print('Ignore DirModified:', event.key)
+            return
+
         src_path = event.src_path
         path = os.path.dirname(src_path)
         for v, p in self.paths.items():