This change exploits phpBB’s hook system which allows us to execute custom code in certain phpBB functions/methods without modifying any files. To do this we need to create a new file in our phpBB installation in the includes/hooks/ directory, the file name must begin with hook_ and end with your PHP extension (usually .php.) So, basically you need to drop the below file into your includes/hooks/ directory and purge the board cache, job done!

includes/hooks/hook_disable-delayed-redirects.php

includes/hooks/hook_enable-debug-for-founders.php

<?php

/**
 * This program is free software. It comes without any warranty, to
 * the extent permitted by applicable law. You can redistribute it
 * and/or modify it under the terms of the Do What The Fuck You Want
 * To Public License, Version 2, as published by Sam Hocevar. See
 * http://sam.zoy.org/wtfpl/COPYING for more details.
 */

if (!defined('IN_PHPBB'))
{
	exit;
}

/**
 * This hook enables the debug mode for founders
 */
function hook_enable_debug_for_founders(&$hook)
{
	global $user;

	if ($user->data['user_type'] == USER_FOUNDER)
	{
		// Be careful when defining the constants

		if (!defined('DEBUG'))
		{
			define('DEBUG', true);
		}

		if (!defined('DEBUG_EXTRA'))
		{
			define('DEBUG_EXTRA', true);
		}
	}
}

$phpbb_hook->register('phpbb_user_session_handler', 'hook_enable_debug_for_founders');

This change exploits phpBB’s hook system which allows us to execute custom code in certain phpBB functions/methods without modifying any files. To do this we need to create a new file in our phpBB installation in the includes/hooks/ directory, the file name must begin with hook_ and end with your PHP extension (usually .php.)

includes/hooks/hook_trusted-users.php:

<?php

/**
 * This program is free software. It comes without any warranty, to
 * the extent permitted by applicable law. You can redistribute it
 * and/or modify it under the terms of the Do What The Fuck You Want
 * To Public License, Version 2, as published by Sam Hocevar. See
 * http://sam.zoy.org/wtfpl/COPYING for more details.
 */

if (!defined('IN_PHPBB'))
{
	exit;
}

/**
 * This hook disables the post queue for accounts registered with a trusted
 * e-mail address.
 */
function hook_trusted_users(&$hook)
{
	global $config, $user;

	/**
	 * Skip when the queue is disabled, or this is an administration
	 * session so we don't break the ACP, chances are that administrators
	 * have moderation permissions or more posts than required to post any way.
	 */
	if ($config['enable_queue_trigger'] && !$user->data['session_admin'] && preg_match('#@example\.com$#i', $user->data['user_email']))
	{
		$config['enable_queue_trigger'] = 0; // Disable the post queue for our trusted users
	}
}

$phpbb_hook->register('phpbb_user_session_handler', 'hook_trusted_users');

Once you have dropped the file in place you will need to purge your cache, or just manually delete cache/data_hooks.php.

function getarchives_filter($where, $args)
{
	if (isset($args['year']))
	{
		$where .= ' AND YEAR(post_date) = ' . intval($args['year']);
	}
	return $where;
}
add_filter('getarchives_where', 'getarchives_filter', 10, 2);

Now the wp_get_archives() function supports a year parameter which restricts results to one particular year. Next we modify the sidebar to make use of this additional argument. Here is an example of the correct call to make:

<?php wp_get_archives('type=monthly&year=' . get_the_time('Y', reset($GLOBALS['posts'])); ?>

This code also works properly when viewing the archives of a particular year, the months outputted change to the currently viewed year.

I have changed my own sidebar code to use this:

<li><h2>Archives</h2>
        <ul>
            <li><strong>Months</strong>
            <ul>
                    <?php
                    // Use the current date when viewing a page, not the pages year
                    $year = (is_page()) ? date('Y') : get_the_time('Y', reset($GLOBALS['posts']));

                    wp_get_archives('type=monthly&limit=12&year[]=' . $year . (!is_archive() ? '&year[]=' . ($year - 1) : ''));
                    ?>
            </ul>
            </li>
            <li><strong>Years</strong>
            <ul>
                    <?php wp_get_archives('type=yearly'); ?>
            </ul>
            </li>
        </ul>
</li>

Updated 31/01/2010: Paul spotted a bug, the code used the date of the last post displayed on the page rather than the first.