I have tested various workarounds for getting GUI stuff as root
(without enabling sudo) for the past week.  Some Debian users are not
comfortable with sudo at all (especially if configured for root access
without password) and prefer the root password to be required for
administration.

I have now settled on a workable solution with Trinity.

Using:

kdesu <kdeapp> --nonewdcop

with the configs I posted earlier has not failed once. (must create
file kdesurc and purge kdesudo-trinity)

It seems the user's dcop and/or klauncher crashes if/when root gets a
new dcop. I don't know why, when I used sudo initially, that did not
happen.

I edited the menu with a new "root apps" section (konq, kwrite, kuser)
configured like that, with "run as different user" unchecked so can
now use terminal, run box or menu.

Non-trinity, gtk apps (synaptic, gparted, zenity) I had problems with
before seem fixed by adding to ~/.bashrc:

export XAUTHORITY=$HOME/.Xauthority

Needed reboot (or relogin) to register that. Don't know if that has
security issues but it works.

I can now open, error-free, as root from terminal or via custom script with:

dbus-launch <gtk-app>

That will not work for trinity apps.

sux gives the same problem as kdesu without --nonewdcop; can't use
that (for Trinity apps) now but never mind