diff -urp advanced_forum/advanced_forum.module advanced_forum_modif/advanced_forum.module
--- advanced_forum/advanced_forum.module	2008-06-10 05:21:48.000000000 +0200
+++ advanced_forum_modif/advanced_forum.module	2008-08-21 17:54:50.000000000 +0200
@@ -104,7 +104,14 @@ function advanced_forum_settings_page() 
     '#description' => t('Choosing yes causes advanced forum to consider every comment a forum comment and attempt to theme it that way. Some changes to your theme may be required.'),
     '#default_value' => variable_get('advanced_forum_theme_all_comments',0),
   );
-
+  //collapsible container
+  $form['advanced_forum_collapse_settings'] = array(
+    '#type' => 'radios',
+    '#title' => t('Choose collapse state'),
+    '#options' => array(t("All collapsed"), t("None collapsed")),
+    '#description' => t('Choose initial collapse state of the forums.'),
+    '#default_value' => variable_get('advanced_forum_collapse_settings', 0)
+  );
   // Send our form to Drupal to make a settings page
   return system_settings_form($form);
 } 
diff -urp advanced_forum/themes/advforum/advanced_forum.css advanced_forum_modif/themes/advforum/advanced_forum.css
--- advanced_forum/themes/advforum/advanced_forum.css	2008-05-28 23:03:07.000000000 +0200
+++ advanced_forum_modif/themes/advforum/advanced_forum.css	2008-08-21 17:33:05.000000000 +0200
@@ -58,6 +58,10 @@
   color: white;
 }
 
+#forum .container span { /*collapsible forum*/
+	cursor: 	pointer; 
+}
+
 #forum td.container a { 
   font-weight: bold;
   color: white;
diff -urp advanced_forum/themes/advforum/advanced_forum-structure.css advanced_forum_modif/themes/advforum/advanced_forum-structure.css
--- advanced_forum/themes/advforum/advanced_forum-structure.css	2008-05-28 23:03:07.000000000 +0200
+++ advanced_forum_modif/themes/advforum/advanced_forum-structure.css	2008-08-21 17:35:58.000000000 +0200
@@ -48,6 +48,11 @@ td.forum {
   line-height: 1.2;
 }
 
+#forum .container span { /*collapsible container*/
+	margin:		0 1em 0 0; 
+	float:		right;
+}
+
 #forum .description {
   padding-left: 0px;
   margin-left: 0;
diff -urp advanced_forum/themes/advforum/advf-forum-list.tpl.php advanced_forum_modif/themes/advforum/advf-forum-list.tpl.php
--- advanced_forum/themes/advforum/advf-forum-list.tpl.php	2008-05-13 06:15:55.000000000 +0200
+++ advanced_forum_modif/themes/advforum/advf-forum-list.tpl.php	2008-08-21 17:44:55.000000000 +0200
@@ -30,7 +30,32 @@
  * @see template_preprocess_forum_list()
  * @see theme_forum_list()
  */
+
+//collapsible container jQuery
+$containerN = 0;
+
+foreach ($forums as $child_id => $forum) //count containers
+	if ($forum->is_container) $containerN += 1;
+
+//create the hideString, for which containers to hide (this should be made much smarter :-), so the user can specify which containers are collapsed at default). An array could specify container collapses.
+if(variable_get('advanced_forum_collapse_settings', 0) == 0) //if zero then collapse, else don't collapse.
+	for ( $counter = 1; $counter <= $containerN; $counter += 1) //create the hide string
+		$jQhide .='$(\'.forum-child-'.$counter.'\').hide();'."\n\t";
+
+for ($counter = 1; $counter <= $containerN; $counter += 1) //create the toggle string
+	$jQtoggle .='$(\'#containerID-'.$counter.'\').click(function(){$(\'.forum-child-'.$counter.'\').toggle()});'."\n\t";
+
+drupal_add_js ( //include the jQuery stuff, don't know if this is the correct place to put this?
+'
+$(document).ready(function() 
+{
+	'."$jQhide$jQtoggle".
+	'return false;
+});',
+'inline'
+);
 ?>
+
 <table id="forum-<?php print $forum_id; ?>">
   <thead>
     <tr>
@@ -44,6 +69,7 @@
   <?php 
   $num_forums = count($forums); 
   $forum_num = 0;
+  $container = 0; //collapsible container
   ?>
   <?php foreach ($forums as $child_id => $forum): ?>
     <?php 
@@ -59,8 +85,9 @@
       default:
         $position = 'middle_row';
     }
+    if ($forum->is_container)$container += 1;//collapsible container
     ?>
-    <tr id="forum-list-<?php print $child_id; ?>" class="<?php print $forum->zebra; ?> <?php print $position;?>">
+    <tr id="forum-list-<?php print $child_id; ?>" class="<?php print $forum->zebra; ?> <?php print $position;?> <?php if (!$forum->is_container) print "forum-child-".$container;?>"> <!-- collapsible container-->
     <td <?php 
         if( $forum->is_container) {
           print 'colspan="4" class="container"';
@@ -76,7 +103,7 @@
                * left-margin for indenting.
                */ ?>
         <?php print str_repeat('<div class="indent">', $forum->depth); ?>
-          <div class="name"><a href="<?php print $forum->link; ?>"><?php print $forum->name; ?></a></div>
+          <div class="name"><a href="<?php print $forum->link; ?>"><?php print $forum->name; ?></a> <?php if ($forum->is_container) print "<span id=\"containerID-".$container."\"> show/hide</span>";?><!--collapsible container--></div>
           <?php if ($forum->description): ?>
             <div class="description"><?php print $forum->description; ?></div>
           <?php endif; ?>