This little patch fixes this :

Index: src/nautilus-sidebar-title.c
===================================================================
RCS file: /cvs/gnome/nautilus/src/nautilus-sidebar-title.c,v
retrieving revision 1.151
diff -u -r1.151 nautilus-sidebar-title.c
--- src/nautilus-sidebar-title.c        13 Jul 2005 12:23:37 -0000      1.151
+++ src/nautilus-sidebar-title.c        14 Jul 2005 16:20:01 -0000
@@ -400,6 +400,7 @@
                return;
        }
        gtk_label_set_text (label, text);
+       gtk_label_set_selectable (label, TRUE);
        update_title_font (sidebar_title);
 }

@@ -469,6 +470,7 @@
        }
        gtk_label_set_text (GTK_LABEL (sidebar_title->details->more_info_label),
                            info_string->str);
+       gtk_label_set_selectable (GTK_LABEL
(sidebar_title->details->more_info_label), TRUE);

        g_string_free (info_string, TRUE);
 }