Edit teaser in separate field?

Hi,

I hope this is not a stupid question. I have been searching for more then an hour. So if this is a duplicate question, please give me a link to the answer.

We would like to edit the teaser of a node in its own textarea.
It seems that fckeditor always joins the teaser and the text.
Is there any setting to get the teaser-field back (with fckeditor enabled) ?

Thanks in advance!
Greetz, Joly