assert(selectall_widget != 0);
assert(selectnone_widget != 0);
assert(properties_widget != 0);
assert(playlists_widget != 0);
assert(playlists_menu != 0);
assert(selectall_widget != 0);
assert(selectnone_widget != 0);
assert(properties_widget != 0);
assert(playlists_widget != 0);
assert(playlists_menu != 0);