Unfortunately still working on that coursework, I've just added support in the API documentation makefile to automatically generate a class hierarchy diagram using the GObject hierarchy file created by gtk-doc and marshalling it to GraphViz. It basically analyses the depth of each line in the hierarchy file and creates relationships in the dot file as appropriate. It doesn't sound complex, but it took a heck of a lot of fiddling to get automake happy with my syntax.

graph-build.stamp:
	echo "digraph class_hierarchy" > $(DOC_MODULE).dot
	echo "{" >> $(DOC_MODULE).dot
	(IFS=$$'\n'; \
	for current_line in `cat $(DOC_MODULE).hierarchy`; do \
		depth_colours=( red green blue yellow ); \
		depth=`echo $$current_line | grep -o "  " | wc -l | sed s/\ //g`; \
		echo "$$current_line [shape=box, color=$${depth_colours[$$depth]}]" >> $(DOC_MODULE).dot; \
		last_line[$$depth]=$$current_line; \
		if [ $$depth -gt 0 ]; then \
			echo "$${last_line[`expr $$depth - 1`]} -> $$current_line" >> $(DOC_MODULE).dot; \
		fi; \
	done)
	echo "}" >> $(DOC_MODULE).dot
	dot -Tpng $(DOC_MODULE).dot > $(DOC_MODULE).png
	touch graph-build.stamp