Edited Issue: HTMLEditorExtender inner item CSS Class disappears [27299]

I know this is a very picky problem but still it exists!
Retro steps:
(you may do this directly on http://www.asp.net/ajaxLibrary/AjaxControlToolkitSampleSite/HTMLEditorExtender/HTMLEditorExtender.aspx)
1- lets start by going into source mode and type this: Hello <b>world!</b><span class="test">This Is A Test</span>
2- switch to design mode
3- focus out of the control (by clicking anywhere else)
4- switch to source mode again and you will see your class disappear (this is not magic... it's a bug)
*This bug is valid for all browser on all versions! (unless i am mistaken but I've tested it in Chrome Firefox IE9 IE8(through IE9) and stopped there :P figured if it worked in <IE8 it was pretty much still a bug on all major browsers)

Thanks