The issue was solved, thanks to the most useful comments by three list participants. The first advice, by Gerhard Zintel, was a suggestion to simply uncheck one of the preferences via the TDE Control Center:

" I had the same issue before. I cannot clearly remember but try to
un-check "Apply colors to non-TDE applications" in TDE Control Center
=> Appearence & Themes => Colors. "


That immediately worked, thanks Gerhard!  But then the next advice came from Nick Koretsky which also commented on the Gerhard's advice:

That's a bad solution - this checkbox is unfortunately named, it should be
named "apply styles' - it govern not only colors, but also button styles,
button placements and fonts in gtk apps

The correct solution is to add following to you .xsession file

(
sleep 10
xrdb -all -query|sed -e 's#[A-Z_]*BACKGROUND# gray90#' \

-e 's#[A-Z_]*FOREGROUND# Black#'  \
-e 's#[A-Z_]*HIGHLIGHT# White#' \
-e 's#[A-Z_]*LOWLIGHT# Black#'|xrdb -merge
) &


I tried this as well, and it works and seems in fact to be more appropriate for our environment. I've applied it by adding to the system-wide script that is executed at login and does it one time per session. It works pretty well (and has no impact on gtk applications). So we'll stick to this method.

Finally, another advice came from "iadest":

Hello
Try to edit ~/.Xresourced adding:

*.WINDOW_FOREGROUND: black

Then execute command:

xrdb -merge ~/.Xresources

I had similar problems with Perl/Tk and *.BACKGROUND color. Maybe this
solution will work for Emacs too.

MCbx

As this solution was basically quite similar to that of Nick's which was already nicely implemented, I did not try this..

In any case, these advices saved me a day. Thanks a lot for all those who replied!

Andy.

------ ORIGINAL MAIL ------
Hello,

I am happily using Trinity since a couple of years, and never had any insolvable issues with it. However, currently I am standing before a "blocker" confguration issue, and would highly appreciate some useful hint/help from the community.

This is what happens:

- I've installed a remote Centos 7 host equipped with a complete Trinity 14.0.3-1.el7.x86_64 desktop. The desktop is being accessed via Freenx and, as this machine will also be used by people with French and German keyboards, the working keyboard switcher apllet present in the 14.03 distro seems to become a really indispensable feature.

- Everyrthing seemingly works well, the desktop looks beautiful, but very soon I discovered that there is a couple off issues. In particular, I cannot start emacs on this machine, it ends up with this error: [ Undefined color: "WINDOW_FOREGROUND" ]. Atfter a bit of googling, it came out that this is a known problem, and it has to do with KDE configuration. People then stated the the issue was essentially solved by simply migrating to the updated version of KDE and no other clues were provided.

- After quite some time spent on searches, I decided to replace "dot.trinity" and "dot.tderc" with their well-customized versions taken from one of my working Centos 6 machines with Trinity 3.5.13-15.1 (which in turn, inherited them from Centos 5 with KDE 3.5.4-1). Surprise: emacs worked like a charm, and also some other issues like remote app submission not working before were gone!

- The old "dot.trinity" configuration, however, has an outdated K-menu, and it does not allow me to add the Keyboard Switcher applet. Thus I have a sort of a "blocker" situation. On one hand, I am almost done with an old "dot.trinity" and may dig in further and try to replace the K-menu under dot.trinity/share/config (this would hopefully give me a chance to add the switcher). Or I have to dig more into the issue of the brand-new install (no good ideas of where to begin, though..)

The funny thing is, there is in fact an almost-working solution. Thus it is only a
TDE configuration issue: something is present, or missing, or set up in a wrong way..

Thanks a lot ahead for any there or a useful hint on how to proceed!

Andy.