glslideshow fails to display images, partial fix found

[SpmP]

glsideshow (/usr/lib/xscreensaver/glslideshow) by default fails to display images other than the 'null' image.
 This behaviour is experienced in other image getting screensavers such as carousel etc.

glslideshow is parsing .xscreensaver correctly as is evident if bogus lines are ammended etc.
imageDirectory: /blah is set correctly

Adding -images to line 77 of glslideshow.c st that the line is:
"*desktopGrabber: xscreensaver-getimage -no-desktop -images %s\n" \
solves the problem for windowed display:
/usr/lib/xscreensaver/glslideshow -duration 8 -pan 8 -fade 4 -zoom 100 -letterbox

With -root as:
/usr/lib/xscreensaver/glslideshow -duration 8 -pan 8 -fade 4 -zoom 100 -letterbox -root
no image is displayed in with unity/copiz manager

With xwinwrap glslideshow fails with:
xwinwrap -ni -argb -fs -o 1 -s -st -sp -b -nf -- /usr/lib/xscreensaver/glslideshow -duration 8 -pan 8 -fade 4 -zoom 100 -letterbox -window-id WID -root
with error:
X error in xscreensaver-getimage:
X Error of farsion from xscreensaveriled request: BadMatch (invalid parameter attributes)
  Major opcode of failed request: 72 (X_PutImage)
  Serial number of failed request: 30
  Current serial number in output stream: 35

Tried with latest vanilla from www.jwz.org, same issues 0 i.e upstream.

Obvouly my motivation is slideshow on the desktop background.
ubuntu 12.10 raring.