Comment 18 for bug 263211

A little digging gives the following:

libgnome-desktop/gnome-bg.c - both the gnome_bg_create_pixmap() and make_root_pixmap() function it calls are largely unchanged since this code was added - however that was only in November 2007 - previously libegg was used

The change to use this function seems to have landed in gnome-screensaver in rev 1434, which is since hardy - however this isn't exactly a one line change! :-(