Add an option to select input format for intro text

It would be nice to be able to use pictures and html formatting in the guestbook introduction. To do this one would like to use some other filter than the default one (which is usually "Filtered HTML"). You can do the same using themes but that's not always convenient.

Providing an additional argument to the check_markup() function in the theme_guestbook(), which is a single line code change, does the thing. However, a proper solution would probably need to include a selection for an administrator just like for the entries filter.

Or maybe something similar will be possible with the new Panels based version 2.0?