standard place for background tiles

[Brian M Dial <bdial rkkengineers com>]

Greetings all,

	Is there a standard place for putting background image for gnome?  I'm
looking to package up the backgrounds from propaganda.themes.org for
future releases of the slackware packages but am not sure where to put
them.  control-center doesn't seem to look in any directory in
particular and I know that users can just browse to whatever directory
you put them in but I wanted to check for a standard (if only de Facto)
now.

Thanks,

-Brian