printing problems: CUPS, claws-mail, firefox and xpdf-4

[Hartmann, O.]

At first, please CC me in your response, I'm not subscribing to the
list.

I have problems printing on FreeBSD CURRENT (12.0-CURRENT #37 r327022:
Wed Dec 20 15:07:55 CET 2017 amd64).

print/cups, graphics/xpdf, mail/claws-mail and www/firefox are of most
recent version as of usr/ports revvision r456793.

The phenomenon is that I can not print via firefox' printing facility
(printer symbol which should open a requester showing all the available
printers), neither via xpdf or claws-mail.

CUPS is up and running ans sockstat indicates, that cupsd is listening

USER     COMMAND    PID   FD PROTO  LOCAL ADDRESS FOREIGN ADDRESS
root     cupsd      28838 5  tcp4   127.0.0.1:631         *:*
root     cupsd      28838 7  stream /var/run/cups.sock

Connecting via firefox and https://localhost:631 works, also printing a
testpage to any printer configured.

The not-so-funny part is that either claws-mail, xpdf or firefox'
printing facility seem to take a long time when selected from menu,
showing then nothing but printing to file. In firefox, it takes ages to
come up with this residual set of printing options, xpdf and claws-mail
are a bit faster.

From the console, lpstat -a shows every configured printer and printing
PS or PDF to a queue from a xterm or console works as expected.

From a Linux forum I gathered some pieces of information regarding the
fact that possibly gtk3 problems may the reason but recompiling the
usual suspicious ports didn't help, even recompiling firefox, xpdf or
claws-mail or poppler/podofo didn't change the situation.

I'm out of ideas. Maybe somebody faces the same problem and has some
hints - I'd appreciate any tip.

Thanks in advance,

Oliver