The best way to create additional pages id by using the Static Pages event plugin. These extra pages then appear in your main window with your plugin bars visible.
They can contain any html you wish.
The other advantage is that they use the same CSS as the rest of your site.

thanks for the ...

I have the exact opposite problem from what is being discussed here. I've embedded serendipity in my web site (still testing and working the bugs out), and would prefer if the details or expanded information (and additional pages) would stay in the same page, so that people do NOT leave my site ...