Textare width

I try to set my ckeditor to a fixed width inside my admin-panel..
without any it looks like:

When i use thw following code to resize the editor it looks like:

config.width='95%';
config.resize_enabled=false;

here is how i call my editor:

<textarea name="opendixckeditor">{$editorvalue}</textarea>
<script type="text/javascript">
            CKEDITOR.replace( 'opendixckeditor',{ 
               filebrowserBrowseUrl : '/browser/browse.php',
                 filebrowserUploadUrl : '/uploader/upload.php' 
                 } );
         </script>

Any idea what I'm doing wrong? Or is there another configuration to est the textare-size?

I used here the latest ckeditor version and i could reproduce this at opera 10.6, IE 8 and FF...