Index: t3lib/config_default.php
===================================================================
--- t3lib/config_default.php	(revision 2932)
+++ t3lib/config_default.php	(working copy)
@@ -174,7 +174,7 @@
 		'AJAX' => array(				// array of key-value pairs for a unified use of AJAX calls in the TYPO3 backend. Keys are the unique ajaxIDs where the value will be resolved to call a method in an object. See ajax.php and the classes/class.typo3ajax.php for more information.
 			'SC_alt_db_navframe::expandCollapse'   => 'typo3/alt_db_navframe.php:SC_alt_db_navframe->ajaxExpandCollapse',
 			'SC_alt_file_navframe::expandCollapse' => 'typo3/alt_file_navframe.php:SC_alt_file_navframe->ajaxExpandCollapse',
-			't3lib_TCEforms_inline::createNewRecord'		=> 't3lib/class.t3lib_tceforms_inline.php:t3lib_TCEforms_inline->processAjaxRequest',
+			't3lib_TCEforms_inline::createNewRecord'		    => 't3lib/class.t3lib_tceforms_inline.php:t3lib_TCEforms_inline->processAjaxRequest',
 			't3lib_TCEforms_inline::setExpandedCollapsedState'	=> 't3lib/class.t3lib_tceforms_inline.php:t3lib_TCEforms_inline->processAjaxRequest',
 			'ShortcutMenu::getGroups'              => 'typo3/classes/class.shortcutmenu.php:ShortcutMenu->getAjaxShortcutGroups',
 			'ShortcutMenu::saveShortcut'           => 'typo3/classes/class.shortcutmenu.php:ShortcutMenu->setAjaxShortcut',
@@ -180,7 +180,8 @@
 			'ShortcutMenu::saveShortcut'           => 'typo3/classes/class.shortcutmenu.php:ShortcutMenu->setAjaxShortcut',
 			'ShortcutMenu::render'                 => 'typo3/classes/class.shortcutmenu.php:ShortcutMenu->renderAjax',
 			'ShortcutMenu::delete'                 => 'typo3/classes/class.shortcutmenu.php:ShortcutMenu->deleteAjaxShortcut',
-			'ShortcutMenu::create'                 => 'typo3/classes/class.shortcutmenu.php:ShortcutMenu->createAjaxShortcut'
+			'ShortcutMenu::create'                 => 'typo3/classes/class.shortcutmenu.php:ShortcutMenu->createAjaxShortcut',
+			'ModuleMenu::saveMenuState'            => 'typo3/classes/class.modulemenu.php:ModuleMenu->saveMenuState'
 		),
 	),
 	'FE' => Array(			// Configuration for the TypoScript frontend (FE). Nothing here relates to the administration backend!
Index: typo3/classes/class.modulemenu.php
===================================================================
--- typo3/classes/class.modulemenu.php	(revision 2932)
+++ typo3/classes/class.modulemenu.php	(working copy)
@@ -105,6 +105,21 @@
 	}
 
 	/**
+	 * saves the menu's toggle state in the backend user's uc
+	 *
+	 * @param	array		array of parameters from the AJAX interface, currently unused
+	 * @param	TYPO3AJAX	object of type TYPO3AJAX
+	 * @return	void
+	 */
+	public function saveMenuState($params, &$ajaxObj) {
+		$menuItem = t3lib_div::_POST('menuid');
+		$state    = t3lib_div::_POST('state') === 'true' ? 1 : 0;
+
+		$GLOBALS['BE_USER']->uc['moduleData']['menuState'][$menuItem] = $state;
+		$GLOBALS['BE_USER']->writeUC();
+	}
+
+	/**
 	 * renders the backend menu as unordered list
 	 *
 	 * @return	string		menu html code to use in the backend
@@ -116,8 +131,9 @@
 		$rawModuleData = $this->getRawModuleData();
 
 		foreach($rawModuleData as $moduleKey => $moduleData) {
+			$menuState   = $GLOBALS['BE_USER']->uc['moduleData']['menuState'][$moduleKey];
+			$moduleLabel = $moduleData['title'];
 
-			$moduleLabel = $moduleData['title'];
 			if($moduleData['link'] && $this->linkModules) {
 				$moduleLabel = '<a href="#" onclick="top.goToModule(\''.$moduleData['name'].'\');'.$onBlur.'return false;">'.$moduleLabel.'</a>';
 			}
@@ -123,11 +139,11 @@
 			}
 
 				//TODO make icon a background image using css
-			$menu .= '<li><div>'.$moduleData['icon']['html'].' '.$moduleLabel.'</div>';
+			$menu .= '<li id="'.$moduleKey.'" class="menuSection"><div>'.$moduleData['icon']['html'].' '.$moduleLabel.'</div>';
 
 				// traverse submodules
 			if(is_array($moduleData['subitems'])) {
-				$menu .= $this->renderSubModules($moduleData['subitems']);
+				$menu .= $this->renderSubModules($moduleData['subitems'], $menuState);
 			}
 
 			$menu .= '</li>'."\n";
@@ -140,9 +156,10 @@
 	 * renders submodules
 	 *
 	 * @param	array		array of (sub)module data
+	 * @param	boolean		collapse state of menu item, defaults to false
 	 * @return	string		(sub)module html code
 	 */
-	public function renderSubModules($modules) {
+	public function renderSubModules($modules, $menuState=false) {
 		$moduleMenu = '';
 		$onBlur     = $GLOBALS['CLIENT']['FORMSTYLE'] ? 'this.blur();' : '';
 
@@ -167,7 +184,7 @@
 			$moduleMenu .= '<li>'.$submoduleLink.'</li>'."\n";
 		}
 
-		return '<ul>'."\n".$moduleMenu.'</ul>'."\n";
+		return '<ul'.($menuState ? ' style="display:none;"' : '').'>'."\n".$moduleMenu.'</ul>'."\n";
 	}
 
 	/**
Index: typo3/js/backend.js
===================================================================
--- typo3/js/backend.js	(revision 2932)
+++ typo3/js/backend.js	(working copy)
@@ -68,6 +68,31 @@
 
 
 
+/**
+ * observes clicks on menuHeader and toggles child ul
+ */
+var ModuleMenuToggle = {
+
+	toggleMenu: function() {
+		$$('li.menuSection div').each(function(element) {
+			element.observe('click', function(){
+				var li    = element.up();
+				var ul    = li.down(2);
+				var state = ul.visible();
+
+					// save state
+				new Ajax.Request('ajax.php', {
+					method: 'post',
+					parameters: 'ajaxID=ModuleMenu::saveMenuState&menuid=' + li.id + '&state=' + state,
+				});
+
+				ul.toggle();
+			});
+		});
+	}
+}
+
+Event.observe(document, 'dom:loaded', ModuleMenuToggle.toggleMenu.bindAsEventListener(ModuleMenuToggle), true);