config.allowedContent = true -> classes still removed

Hey Community,

i added allowedContent : true  to my Code but

<p class="foo">Bar</p>

is still changed to

<p>Bar</p> :(

WHY?

thx for any hints...

<script type="text/javascript">
			<!-- //

			CKEDITOR.replace( 'message',
			{
				extraPlugins : 'autogrow',
				autoGrow_maxHeight : 800,
				allowedContent : true
			});
                        //var editor = CKEDITOR.replace('message');
		//-->
		</script>