The xloadimage(1) reads, in part:

EXAMPLES
       [...]
       To center an image on the default root background:

            xloadimage -default -tile my.image

This does not work.  Instead, it causes the root window to become black
except for four white pixels (in the X weave pattern) in the upper-left
corner.


Other things I was not able to do:

- Load an image centred on the root window with a solid border.

- Do a slide show on the root window (when using -onroot, '-global
  -delay 5' had no effect; instead, '-merge' seemed to be in effect).

- Use '-default -tile -dither my.image' - this caused a segfault,
  though '-onroot -dither my.image' was O.K.

(Perhaps these just require non-obvious combinations of switches?
Please let me know if I need to RTFM again.  I mean, I've only read it
about five times so far.)