Index: typo3/sysext/install/updates/class.tx_coreupdates_t3skin.php
===================================================================
--- typo3/sysext/install/updates/class.tx_coreupdates_t3skin.php	(revision 7980)
+++ typo3/sysext/install/updates/class.tx_coreupdates_t3skin.php	(working copy)
@@ -42,13 +42,14 @@
 	 * @return	boolean		whether an update is needed (true) or not (false)
 	 */
 	public function checkForUpdate(&$description) {
+		$result = FALSE;
 		$description = '<strong>The backend skin "t3skin" is not loaded.</strong>
 		TYPO3 4.4 introduced many changes in backend skinning and old backend skins are now incompatible.
 		<strong>Without "t3skin" the backend may be unusable.</strong> Install extension "t3skin".';
 		if (!t3lib_extMgm::isLoaded('t3skin')) {
-			return TRUE;
+			$result = TRUE;
 		}
-		return FALSE;
+		return $result;
 	}
 
 	/**
@@ -71,21 +72,68 @@
 	 * @return	bool		whether everything went smoothly or not
 	 */
 	public function performUpdate(array &$dbQueries, &$customMessages) {
+		$result = FALSE;
 		if ($this->versionNumber >= 4004000 && !t3lib_extMgm::isLoaded('t3skin')) {
 			// check wether the table can be truncated or if sysext with tca has to be installed
 			if ($this->checkForUpdate($customMessages[])) {
-				$localconf = $this->pObj->writeToLocalconf_control();
-				$this->pObj->setValueInLocalconfFile($localconf, '$TYPO3_CONF_VARS[\'EXT\'][\'extList\']', $GLOBALS['TYPO3_CONF_VARS']['EXT']['extList'] . ',t3skin');
-				$message = $this->pObj->writeToLocalconf_control($localconf);
+				$extList = $this->addExtToList(array('t3skin'));
+				if ($extList) {
+					$message = $this->writeNewExtensionList($extList);
+				}
+
 				if ($message == 'continue') {
 					$customMessages = 'The system extension "t3skin" was succesfully loaded.';
-					return TRUE;
-				} else { 
-					return FALSE;	// something went wrong
+					$result = TRUE;
 				}
+				}
 			}
-			return TRUE;
+		return $result;
+	}
+
+	/**
+	 * Adds extension to extension list and returns new list. If -1 is returned, an error happend.
+	 * Does NOT check dependencies yet.
+	 *
+	 * @param	array		Extension keys to add
+	 * @return	string		New list of installed extensions or -1 if error
+	 */
+	protected function addExtToList(array $extKeys) {
+			// Get list of installed extensions and add this one.
+		$tmpLoadedExt = $GLOBALS['TYPO3_LOADED_EXT'];
+		if (isset($tmpLoadedExt['_CACHEFILE'])) {
+			unset($tmpLoadedExt['_CACHEFILE']);
 		}
+
+		$listArr = array_keys($tmpLoadedExt);
+		$listArr = array_merge($listArr, $extKeys);
+
+			// Implode unique list of extensions to load and return:
+		return implode(',', array_unique($listArr));
+		}
+
+
+	/**
+	 * Writes the extension list to "localconf.php" file
+	 * Removes the temp_CACHED* files before return.
+	 *
+	 * @param	string		List of extensions
+	 * @return	string		Result of writeToLocalconf_control()
+	 */
+	protected function writeNewExtensionList($newExtList)	{
+			// Instance of install tool
+		$instObj = new t3lib_install;
+		$instObj->allowUpdateLocalConf = 1;
+		$instObj->updateIdentity = 'TYPO3 Core Update Manager';
+
+			// Get lines from localconf file
+		$lines = $instObj->writeToLocalconf_control();
+		$instObj->setValueInLocalconfFile($lines, '$TYPO3_CONF_VARS[\'EXT\'][\'extList\']', $newExtList);
+		$result = $instObj->writeToLocalconf_control($lines);
+
+		$GLOBALS['TYPO3_CONF_VARS']['EXT']['extList'] = $newExtList;
+		t3lib_extMgm::removeCacheFiles();
+
+		return $result;
 	}
 }
 ?>
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