Updating to civi 4.6 after this can't create new emails no text editor
Found a solution: The problems is K2. k2.php was not correct coded. 

See plugins/system/k2.php - specifically this code section:

if (JString::strpos($response, 'prefix="og: http://ogp.me/ns#"') === false) 
                    { 
                            $searches[] = ''; 
                            $replacements[] = 'http://ogp.me/ns#" '; 
                            $replacements[] = 'http://ogp.me/ns#">'; 
                    }

Change this to:

$app =&amp; JFactory::getApplication(); 
            if ($app->isSite()){ 

                if (JString::strpos($response, 'prefix="og: http://ogp.me/ns#"') === false) 
                { 
                        $searches[] = '&lt;html '; 
                                $searches[] = '&lt;html&gt;'; 
                        $replacements[] = '&lt;html prefix="og: http://ogp.me/ns#" '; 
                        $replacements[] = '&lt;html prefix="og: http://ogp.me/ns#"&gt;'; 
                } 
        } 


Thanks to "plethoradesign" 

Now the editor appears but somehow all drop down box options are not clickable meaning you can't select a group nor templates and also you can't jump to the next step. Help is still needed. Best P