Please describe the problem:
I've been trying to write a simple Python plugin that would allow me to choose a random artist or album from my library. While prototyping it in Python console everything worked OK. After wrapping it as a Plugin it stopped. Running a random_artist() method spawns many warnings and criticals:

(11:41:39) [0x6c9500] [Randomizer.random_artist] /home/doomhammer/.gnome2/rhythmbox/plugins/randomizer/randomizer.py:107: Enter random_artist
(11:41:39) [0x6c9500] [Randomizer.random_artist] /home/doomhammer/.gnome2/rhythmbox/plugins/randomizer/randomizer.py:113: Alan Menken
(11:41:39) [0x6c9500] [Randomizer.random_artist] /home/doomhammer/.gnome2/rhythmbox/plugins/randomizer/randomizer.py:117: And now set_selection()

(rhythmbox:5934): GLib-GObject-WARNING **: invalid unclassed pointer in cast to `GtkObject'

(rhythmbox:5934): GLib-GObject-WARNING **: invalid unclassed pointer in cast to `GtkObject'

(rhythmbox:5934): GLib-GObject-WARNING **: invalid unclassed pointer in cast to `GtkObject'

(rhythmbox:5934): GLib-GObject-WARNING **: invalid unclassed pointer in cast to `GtkObject'

(rhythmbox:5934): GLib-GObject-WARNING **: invalid unclassed pointer in cast to `GtkObject'

(rhythmbox:5934): GLib-GObject-WARNING **: instance with invalid (NULL) class pointer

(rhythmbox:5934): GLib-GObject-CRITICAL **: g_signal_emit_valist: assertion `G_TYPE_CHECK_INSTANCE (instance)' failed

(rhythmbox:5934): GLib-GObject-WARNING **: invalid unclassed pointer in cast to `GtkObject'

(rhythmbox:5934): GLib-GObject-WARNING **: instance with invalid (NULL) class pointer

(rhythmbox:5934): GLib-GObject-CRITICAL **: g_signal_handlers_destroy: assertion `G_TYPE_CHECK_INSTANCE (instance)' failed

(rhythmbox:5934): GLib-GObject-WARNING **: instance with invalid (NULL) class pointer

(rhythmbox:5934): GLib-GObject-CRITICAL **: g_signal_handlers_destroy: assertion `G_TYPE_CHECK_INSTANCE (instance)' failed

(rhythmbox:5934): GLib-GObject-WARNING **: invalid uninstantiatable type `<invalid>' in cast to `GtkObject'

(rhythmbox:5934): GLib-GObject-WARNING **: invalid uninstantiatable type `<invalid>' in cast to `GtkObject'

(rhythmbox:5934): GLib-GObject-WARNING **: invalid uninstantiatable type `<invalid>' in cast to `GtkObject'

(rhythmbox:5934): GLib-GObject-WARNING **: invalid uninstantiatable type `<invalid>' in cast to `GtkObject'

(rhythmbox:5934): GLib-GObject-WARNING **: invalid uninstantiatable type `<invalid>' in cast to `GtkObject'

(rhythmbox:5934): GLib-GObject-WARNING **: instance of invalid non-instantiatable type `<invalid>'

(rhythmbox:5934): GLib-GObject-CRITICAL **: g_signal_emit_valist: assertion `G_TYPE_CHECK_INSTANCE (instance)' failed

(rhythmbox:5934): GLib-GObject-WARNING **: invalid uninstantiatable type `<invalid>' in cast to `GtkObject'

(rhythmbox:5934): GLib-GObject-WARNING **: instance of invalid non-instantiatable type `<invalid>'

(rhythmbox:5934): GLib-GObject-CRITICAL **: g_signal_handlers_destroy: assertion `G_TYPE_CHECK_INSTANCE (instance)' failed

(rhythmbox:5934): GLib-GObject-WARNING **: instance of invalid non-instantiatable type `<invalid>'

(rhythmbox:5934): GLib-GObject-CRITICAL **: g_signal_handlers_destroy: assertion `G_TYPE_CHECK_INSTANCE (instance)' failed

(rhythmbox:5934): GLib-GObject-WARNING **: invalid cast from `(null)' to `GtkObject'

(rhythmbox:5934): GLib-GObject-WARNING **: invalid cast from `(null)' to `GtkObject'
(rhythmbox:5934): GLib-GObject-WARNING **: invalid cast from `(null)' to `GtkObject'

(rhythmbox:5934): GLib-GObject-WARNING **: invalid cast from `(null)' to `GtkObject'

(rhythmbox:5934): GLib-GObject-WARNING **: invalid cast from `(null)' to `GtkObject'

(rhythmbox:5934): GLib-GObject-WARNING **: /build/buildd/glib2.0-2.14.0/gobject/gsignal.c:2133: signal id `2' is invalid for instance `0xc56ce0'

(rhythmbox:5934): GLib-GObject-WARNING **: invalid cast from `(null)' to `GtkObject'

(rhythmbox:5934): Rhythmbox-CRITICAL **: rb_property_view_get_model: assertion `RB_IS_PROPERTY_VIEW (view)' failed

(rhythmbox:5934): GLib-GObject-CRITICAL **: g_object_get: assertion `G_IS_OBJECT (object)' failed
Segmentation fault (core dumped)


Steps to reproduce:
import rhythmdb, rb
import gtk
import random

ui_str = """
<ui>
  <menubar name="MenuBar">
	<menu name="ControlMenu" action="Control">
	  <menuitem name="RandomArtist" action="RandomArtist"/>
	  <menuitem name="RandomAlbum" action="RandomAlbum"/>
	</menu>
  </menubar>
</ui>
"""

class Randomizer(rb.Plugin):

	def __init__(self):
		rb.Plugin.__init__(self)

	def activate(self, shell):
		self.shell = shell
		self.artist_action = gtk.Action ('RandomArtist', _('Random Artist'), _(''), None)
		self.activate_id = self.artist_action.connect ('activate', self.random_artist, shell)
		
		self.album_action = gtk.Action ('RandomAlbum', _('Random Album'), _(''), None)
		self.activate_id = self.album_action.connect ('activate', self.random_album, shell)
		
		self.action_group = gtk.ActionGroup ('RandomizerPluginActions')
		self.action_group.add_action_with_accel (self.artist_action,
				"<control>T")

		self.action_group.add_action_with_accel (self.album_action,
				"<control>M")
		
		uim = shell.get_ui_manager ()
		uim.insert_action_group (self.action_group, 0)
		self.ui_id = uim.add_ui_from_string (ui_str)
		uim.ensure_update ()
		self.db = self.shell.props.db
		self.source = self.shell.props.library_source
		self.artists = list()
		self.albums = list()

	def deactivate(self, shell):
		del self.shell
		del self.db
		del self.source
		del self.artists
		del self.albums
		pass

	def random_artist(self, action, shell):
		print "Enter random_artist"
		for row in self.source.props.query_model:
			entry = row[0]
			self.artists.append(self.db.entry_get(entry, rhythmdb.PROP_ARTIST))

		random_artist = random.choice(self.artists)
		print random_artist

		for view in self.source.get_property_views():
			if view.props.prop == rhythmdb.PROP_ARTIST:
				# Lack of get_property_view() method
				print "And now set_selection()"
				view.set_selection([random_artist])


	def random_album(self, action, shell):
		for row in self.source.props.query_model:
			entry = row[0]
			self.albums.append(self.db.entry_get(entry, rhythmdb.PROP_ALBUM))

		random_album = random.choice(self.albums)

		for view in self.source.get_property_views():
			if view.props.prop == rhythmdb.PROP_ALBUM:
				view.set_selection([random_album])


Actual results:
Segmentation fault (core dumped)

Expected results:


Does this happen every time?


Other information: