[pygtk] Compiling Pango from git needs GTK-Doc which needs docbook DTD

[Greg Ewing]

It turns out that the currently released version of Pango
is not quite up to snuff -- it's missing some annotations
on method arguments that leads gobject introspection astray.

It looks like these have been fixed in the git repository,
so I tried to check it out and compile it, and discovered
that it wants GTK-Doc.

So I got GTK-Doc and tried to compile that, and it complained
about not being able to find an XML DTD for DocBook.

What do I need to install to get that? The only thing I've
been able to find for download called 'docbook' is just a
zip file with no indication of where to install stuff.

-- 
Greg