[pitivi/ges: 206/287] Rename _checkUsedSource to _sourceIsUsed and document

[Jean-FranÃois Fortin Tam <jfft src gnome org>]

commit 98aa649d2c04e6358387de6cf2ec5bd4a9e1f791
Author: Jean-FranÃois Fortin Tam <nekohayo gmail com>
Date:   Wed Jan 11 12:46:10 2012 -0500

    Rename _checkUsedSource to _sourceIsUsed and document

 pitivi/medialibrary.py |    7 ++++---
 1 files changed, 4 insertions(+), 3 deletions(-)
---
diff --git a/pitivi/medialibrary.py b/pitivi/medialibrary.py
index 13eeda4..dd4e7a9 100644
--- a/pitivi/medialibrary.py
+++ b/pitivi/medialibrary.py
@@ -876,8 +876,9 @@ class MediaLibraryWidget(gtk.VBox, Loggable):
             self.app.current.sources.removeUri(uri)
         self.app.action_log.commit()
 
-    def _checkUsedSource(self, timeline, uri):
-        layers = timeline.get_layers()
+    def _sourceIsUsed(self, uri):
+        """Check if a given URI is present in the timeline"""
+        layers = self.app.current.timeline.get_layers()
         for layer in layers:
             for tlobj in layer.get_objects():
                 if tlobj.get_uri() == uri:
@@ -894,7 +895,7 @@ class MediaLibraryWidget(gtk.VBox, Loggable):
         model = self.storemodel
         selection = self.treeview.get_selection()
         for source in sources:
-            if not self._checkUsedSource(self.app.current.timeline, source.get_uri()):
+            if not self._sourceIsUsed(source.get_uri()):
                 unused_sources_uris.append(source.get_uri())
 
         # Hack around the fact that making selections (in a treeview/iconview)