Update: Before start working in a module, check that It’s not already deprecated (like CList or CTree): these modules will be removed in GTK+3 so the doc migration is not needed
One of the tasks to improve the GTK+/Glib docs maintenance is to convert the documentation from templates (*.sgml) files into source-comments. This is a easy tasks that everybody can do.
All the process is documented here: 
Here a step-by-step example to help new contributors 😉
- Download GTK+ and gtk-doc source code:
git clone git://git.gnome.org/gtk-doc
git clone git://git.gnome.org/gtk+
- Execute gtk-doc script to convert the documentation
This creates a “src” directory containing “*.c” files with all the comments.
- Copy and paste them to the right place.
The section docs are best placed in the *.c file. Put them below the copyright header and the main includes (if there is no *.c file use the appropriate *.h file).
All other comment blocks should be put directly above the definition of the symbol.
For example, for
GtkAccelGroup, we’d move the comments from
- Remove the template file:
git rm docs/reference/gtk/tmpl/gtkaccelgroup.sgml
- Check that the documentation is correctly generated with:
then go with a browser to docs/reference/gtk/html
- Send a patch to bugzilla and make it block 599599 for GTK+ or 589775 for Glib documentation.
- Update the wiki page  to avoid duplicate work
When adding the source code comment, its a good opportunity to review it a bit. Have a look on spelling and style. Is it really giving a helpful explanation what the function does, etc. Also improve cross references. The gtk-doc syntax of the comments is described in the gtk-doc manual .
You can take a look to the gtkwidget.h  and gtkwidget.c  code as an example.