1. Count your forum containers ...
2. Using a text editor, create a Java script file, gave it a name, for example: collapse-containers.js using the following code, and put it in the /misc folder :

   " Note : the following code is for 11 containers , count the containers in your forum and place the corresponding definitions after the first line "var containers = { };" of the Java script code. If you want to make new containers later , you need to edit this file in the future "

   var containers = { };
   containers["container_1"] = { "show" : 1 };
   containers["container_2"] = { "show" : 1 };
   containers["container_3"] = { "show" : 1 };
   containers["container_4"] = { "show" : 1 };
   containers["container_5"] = { "show" : 1 };
   containers["container_6"] = { "show" : 1 };
   containers["container_7"] = { "show" : 1 };
   containers["container_8"] = { "show" : 1 };
   containers["container_9"] = { "show" : 1 };
   containers["container_10"] = { "show" : 1 };
   containers["container_11"] = { "show" : 1 };
   
   function elwardah_forum_class_filter(r, m) {
     m = " " + m + " ";
     var tmp = [];
     for (var i = 0; r[i]; i++) {
       var pass = (" " + r[i].className + " ").indexOf(m) >= 0;
       if (pass) {
         tmp.push(r[i]);
       }
     }
     return tmp;
   }
   
   function elwardah_forum_toggle_display(m) {
     containers[m]["show"] = !containers[m]["show"];
   
     elwardah_forum_render(m);
   
     elwardah_forum_store_preferences();
   };
   
   function elwardah_forum_render(m) {
     var rows = document.getElementsByTagName("tr");
     rows = elwardah_forum_class_filter(rows, m);
   
     for ( var i = 0; rows[i]; i++ ) {
       if (containers[m]["show"]) {
         elwardah_forum_show(rows[i]);
       } else {
         elwardah_forum_hide(rows[i]);
       }
     }
   
     var c = document.getElementById(m);
     var e = c.getElementsByTagName("span");
     e = elwardah_forum_class_filter(e, "show_hide_message");
     e[0].innerHTML = containers[m]["show"] ? "Hide" : "Show";
   }
   
   function elwardah_forum_hide(e) {
     e.oldblock = e.oldblock || e.style.display;
     if (e.oldblock == "none") {
       e.oldblock = "block";
     }
     e.style.display = "none";
   }
   
   function elwardah_forum_show(e) {
     e.style.display = e.oldblock ? e.oldblock : "";
     if (e.style.display == "none") {
       e.style.display = "block";
     }
   }
   
   function elwardah_forum_store_preferences() {
     var data = [];
     for (var c in containers) {
       data.push(c + ":" + Number(containers[c]["show"]));
     }
     data = escape(data.join(";"));
   
     var date = new Date();
     date.setTime(date.getTime() + (365*24*60*60*1000));
     var expires = "; expires=" + date.toGMTString();
     document.cookie = "forumprefs=" + data + expires + "; path=/";
   }
   
   function elwardah_forum_load_preferences() {
     var cookieName = "forumprefs=";
     var ca = document.cookie.split(";");
     for(var i = 0; i < ca.length; i++) {
       var c = unescape(ca[i].replace(/^\s+|\s+$/g, ""));
       if (c.indexOf(cookieName) == 0) {
         var data = c.substring(cookieName.length, c.length);
         data = data.split(";");
         for (var k = 0; data[k]; k++) {
           var pair = data[k].split(":");
           if (containers[pair[0]]) {
             containers[pair[0]]["show"] = Number(pair[1]);
           }
         }
       }
     }
   
     for (var c in containers) {
       elwardah_forum_render(c);
     }
   }
   
   function elwardah_stop_bubble(e) {
     if (e.stopPropagation) e.stopPropagation(); e.cancelBubble = true;
   }
   

3. Using a text editor, create a file and give it the name "forum_list.tpl.php" using the following code. Put it in your active theme folder.

   <?php
   /**
   * This snippet generates the forum_list layout.
   * This works with Drupal 4.7 and Drupal 5.x
   * For use with a custom forum_list.tpl.php file.
   *
   */
   
     global $user; // checks the current user so later the snippet can determine what permissions they have
   
     if ($forums) { // check if there is forums.
   
         drupal_add_js("misc/collapse-containers.js");  // include the Java script file in the pages that has forums
   
             $container_flag = 0;                  
   
       foreach ($forums as $key=>$forum) { // this is the start of the forum list routine that generates the containers and forum list.
   
         if ($forum->container) {          // If the forum is a container
   
            
             if ($container_flag) {  // I wanted each container to be in a separate table
                     print theme('table', $header, $rows);
                 $rows = $nrows;
             }
               $container_flag += 1;
      
           $description  = "<div>\n";
           $description .= ' <div class="name">'. l($forum->name, "forum/$forum->tid/container") ."</div>\n";
           if ($forum->description) {
             $description .= " <div class=\"description\">$forum->description</div>\n" ;
           }
   
           $description .= "<span class=\"show_hide_message\">Show</span>"."</div>\n";
       $rows[] = array( 'class' => 'container', 'data' => array('data' => array( 'data' => $description,'colspan' =>4)), 'id'=>'container_'.$container_flag, 'onclick'=>"elwardah_forum_toggle_display(this.id);" );
      
       // this sets the column titls and style sheet class names
           $rows[] = array('class' => 'container_'.$container_flag, 'data' =>array(
           array('data' => t('Subject'), 'class' => 'f-subject'),
           array('data' => t('Topics'), 'class' => 'f-topics'),
           array('data' => t('Posts'),'class' => 'f-posts'),
           array('data' => t('Last post'),'class' => 'f-last-reply')
           ));
   
   
         }
         else {                     // If the forum is not a container
           $forum->old_topics = _forum_topics_unread($forum->tid, $user->uid);
           if ($user->uid) {
             $new_topics = _forum_topics_unread($forum->tid, $user->uid);
           }
           else {
             $new_topics = 0;
           }
           $description  = '<div>';
           $description .= ' <div class="name">'. l($forum->name, "forum/$forum->tid") ."</div>\n";
           if ($forum->description) {
             $description .= " <div class=\"description\">$forum->description</div>\n";
           }
           $description .= "</div>\n";
           $rows[] = array( 'class' => 'container_'.$container_flag, 'data' =>array(
             array('data' => $description, 'class' => 'forum'),
             array('data' => $forum->num_topics . ($new_topics ? '<br>'. l(format_plural($new_topics, '1 new', '@count new'), "forum/$forum->tid", NULL, NULL, 'new') : ''), 'class' => 'topics'),
             array('data' => $forum->num_posts, 'class' => 'posts'),
             array('data' => _forum_format($forum->last_post), 'class' => 'last-reply')));
         }
       }
       /**
        * Only set the table header if page is a container with listing of forums
        */
       if(in_array(arg(1), variable_get('forum_containers', array()))){
               // reverse array
               $nrows = array_reverse($rows,true);
               //get the container description
               $container = taxonomy_get_term(arg(1));
               //add to output
               $rows = $nrows;
               $rows[] = array( 'class' => 'container_'.$container_flag, 'data' =>array(
                   array('data' => t('Subject'), 'class' => 'f-subject'),
                   array('data' => t('Topics'), 'class' => 'f-topics'),
                   array('data' => t('Posts'),'class' => 'f-posts'),
                   array('data' => t('Last post'),'class' => 'f-last-reply')
                   ));
               $rows[] = array( 'class' => 'container', 'data' => array('data' => array( 'data' => $description,'colspan' =>4)), 'id'=>'container_'.$container_flag, 'onclick'=>"elwardah_forum_toggle_display(this.id);" );
               //reverse again to output
               $nrows = array_reverse($rows,true);
               $rows = $nrows;
           }     
       print theme('table', $header, $rows);
     
     }
   ?>
   

4. In a text editor, create a new file called "template.php" and copy the following snippet into the file. If a "template.php" file already exists, simply add the snippet remembering to omit the opening and closing PHP tags (i.e. and )

   <?php
   /**
   * This snippet tells Drupal to override the forum_list function
   * and load a custom forum_list.tpl.php layout file
   * in the theme folder
   */
   function phptemplate_forum_list($forums, $parents, $tid) {
   return _phptemplate_callback('forum_list', array('forums' => $forums, 'parents' =>$parents, 'tid' =>$tid));
   }
   ?>
   

5. Make the required addition to your css file to stylish the "show_hide_message" class, for example:

   show_hide_message {
                               float: left;
                               color:#fff;
                               font-size:1.6em;
                               font-weight:bold;
                               }
   

6. The result can be found here :

   http://www.elwardah.com/forum

Note : The idea was inspired by the forum of :

http://gallery.menalto.com/forum