Add a check on the filter argument, instead of blindly passing it to

Add a check on the filter argument, instead of blindly passing it to

2006-08-14  Emmanuele Bassi  <ebassi@gnome.org>

	* gtk/gtkrecentchooser.c:
	(gtk_recent_chooser_add_filter),
	(gtk_recent_chooser_remove_filter),
	(gtk_recent_chooser_set_filter): Add a check on the
	filter argument, instead of blindly passing it to
	underlying implementation.

	* gtk/gtkrecentchoosermenu.c:
	(gtk_recent_chooser_menu_add_filter),
	(gtk_recent_chooser_menu_remove_filter),
	(gtk_recent_chooser_menu_list_filters): Implement
	these GtkRecentChooser methods, by setting and
	returning the only GtkRecentFilter object supported
	by a GtkRecentChooserMenu. (#347856, reported by Rod
	Butcher)