Although currently hidden in CVS, the manual is taking shape now. Few weeks, I was searching for some function that would convert between national charset and UTF-8. But I didn't find any that worked both on Linux and Windows. But it's not a problem to add some more. You can download it here and use it freely in your applications.
Usage is very simple.
If you're using ISO8859-2, you don't have to specify charset. Please, send me any comments or suggestions. I just recieved my CVS account at php.net and will probably, with the help of Jared, be moving this site over to the official site - gtk.php.net . This isn't necessarily a PHP-GTK question, but does relate. Over the past few days everything has finally come together, and it is now possible to start producing the xml doc files on either 'nix or win32.