It's sad on the bug, that RiscOS theme supplied
with tde doesn't
work
either (see the screenshot).
So it seems to be a bug somewhere deep inside tdelibs or qt3.
I ran some tests and filed a comment in the bug report (1609). The
pixmaps do not show in 3.5.10 either, so pixmaps have been broken
for a while. The kinstalltheme command never gets run when creating
a new profile. In a new profile, only after manually running
kinstalltheme did I finally see riscos in the kcontrol drop-down
list.
Darrell