Ok fixed that, here is how:

edit in:
/usr/share/applications/gtklp.desktop
/usr/share/applications/hildon/gtklp.desktop

Change the line that says
to
(I am sure this is some simple way of dealing with the
sort of reticulated convolutions and backflip-handstands
required for Hildon/osso-mime-type/ or whatever it is so
deeply hidden in the documentation I have not yet found it setting)

voila - the gtklp desktop icon will now launch with the file selection
menu intact, ready for your printing pleasure.


Other news,
downloaded the latest bleeding edge Fennec (firefox)
and see the print dialogue is available only on websites which
have a print button,
but it has the Firefox "save to pdf" feature which means printing
webpages is just a couple of clicks of detour. (MicroB does not)


Ditto for gnumeric - just save to pdf I guess,
but not sure yet how you can ensure the page format is correctly
arrived at...

My next task is to get the default print dialogue working
that already exists in evince, leafpad, etc.

printcap checked
gtk-print-backend checked
what next?

gtklp works and those others do not - what is the difference
in the way gtklp calls up the printcap info
as compared to these others?
I think it must be something simple, but who knows...