WordPress.org

IMPORTANT! Please deactivate before upgrading, then re-activate the plugin.

MANUAL INSTALLATION (the only option for pre 2.3 wordpress, unless you have the widget plugin installed)

Unpackage contents to wp-content/plugins/ so that the files are in a collapsPage directory. Now enable the plugin. To use the plugin, change the following where appropriate (most likely sidebar.php):

<ul>
     <?php wp_list_pages(...); ?>
</ul>

To something of the following:

    <?php
  echo "<ul>\n";
      if( function_exists('collapsPage') ) {
      collapsPage();
    } else {
      wp_list_pages(...);
    }
  echo "</ul>\n";
    ?>

You can specify options if you wish. See the options section.

The above will fall back to the WP function for pages if you disable the plugin.

WIDGET INSTALLATION

For those who have widget capabilities, (default in Wordpress 2.3+), installation is easier.

Unzip contents to wp-content/plugins/ so that the files are in a collapsing-pages directory. You must enable the Collapsing Pages plugin, then simply go the Presentation > Widgets section and add the Collapsing Pages Widget.