private static void pruneOldWindowPreferences(Preferences prefs) {
		// 45 days ago, in milliseconds
		long cutoff = System.currentTimeMillis() - 1000L * 60L * 60L * 24L * 45L;
		List<String> keys = prefs.getModuleKeys(WINDOW_PREFERENCES);
		ArrayList<String> list = new ArrayList<>();
		for (String key : keys) {
			if (key.endsWith(KEY_LAST_UPDATED)) {
				if (prefs.getLongValue(WINDOW_PREFERENCES, key, 0) < cutoff) {
					list.add(key.substring(0, key.length() - KEY_LAST_UPDATED.length()));
				}
			}
		}
		if (!list.isEmpty()) {
			for (String key : keys) {
				for (String prefix : list) {
					if (key.startsWith(prefix)) {
						prefs.removePreference(WINDOW_PREFERENCES, key);
						break;
					}
				}
			}
		}
	}