[kupfer] plugin.volumes: Implement Volume.is_valid

[Ulrik Sverdrup <usverdrup src gnome org>]

commit 7f5021995d358dd8d4f49cc833e192798e531405
Author: Ulrik Sverdrup <ulrik sverdrup gmail com>
Date:   Wed Sep 9 00:25:10 2009 +0200

    plugin.volumes: Implement Volume.is_valid
    
    So that Volumes disappear from selection when unmounted by going
    invalid.

 kupfer/plugin/volumes.py |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)
---
diff --git a/kupfer/plugin/volumes.py b/kupfer/plugin/volumes.py
index cee8328..f629c25 100644
--- a/kupfer/plugin/volumes.py
+++ b/kupfer/plugin/volumes.py
@@ -28,6 +28,10 @@ class Volume (Leaf):
 	def content_source(self, alternate=False):
 		return objects.DirectorySource(self.object, show_hidden=alternate)
 
+	def is_valid(self):
+		vm = gio.volume_monitor_get()
+		return any(self.volume == v for v in vm.get_mounts())
+
 	def get_description(self):
 		return _("Volume mounted at %s") % self.object
 	def get_gicon(self):