The ../examples directory contains a good deal of code which implicitly
tests the SLgtk module.


While the --auto switch is especially helpful here, additional automated 
tests would be useful.  Among others, these might include:

	- calling each func with a no args, to generate a usage() message.
	- call *_create_tag() with asymmetric name/value property "pairs"
	- pixbuf_from_file with no file, unreadable file, etc
