This is behavior of tinyMCE original widget. And we do not changed widget client side functionality but just wrapped it to JSF components. So please check tineMCE resources on such qeuestions.
Well I think that as a java developers, and espcially JSF developers that wants to use richfaces components without even care about the underline components this forums is exactly the place to ask and answer such questions.
But since my question was not answered I needed to dig in and find the solution myself. so here is the solution for future use:
I found a site with all the tinyMCE possible configurations: http://wiki.moxiecode.com/index.php/TinyMCE:Configuration
you can use the rich:editor f:param child element to define the tinyMCE configureation
for example if you want to disable the paragraph addition after every enter you can use:
<f:param name="force_p_newlines " value="false"/>
<f:param name="force_br_newlines " value="true"/>
<f:param name="forced_root_block " value=""/>
If you want to set CSS style for the inner editor panel you need to define the css file using another param element:
<f:param name="content_css" value="[the css file path]"/>
In the CSS you can set things like the font style (size, color)
thank you, guy
so kind of you GGWP