Geoff

However va-driver-all is marked as a broken package as it depends on mesa-va-drivers.

E: /var/cache/apt/archives/mesa-va-drivers_18.3.4-2_amd64.deb: trying to overwrite '/usr/lib/x86_64-linux-gnu/dri/nouveau_drv_video.so', which is also in package vdpau-va-driver:amd64 0.7.4-dmo6

Using the aptitude command which fsmithred supplied I looked for packages not in testing :-

aptitude search ~i -F"%p# %v# %t#"|grep -v testing
returns a lot of packages, (about 100 according to wc).

I then used Synaptic to carry out the tidying up.

I forced the version of upower to 0.99.10-1 which counts as a downgrade!
It also removes va-driver-all and moves to libupower-glib3, which gets rid of the broken package problem.
I downgraded vdpau-va-driver to the Beowulf version.

As I am using LXQt instead of LXDE, I removed the LXDE components.

I had consolekit installed as well as elogind, so remove consolekit,
which does some other sorting out of libpolkit stuff.
Initially the shutdown icon only logged me out, but with libpolkit sorted out, shutdown now works.

The old gksu from ASCII is still installed and works!

apt-get autoremove does some minor tidying up.

Where possible I forced versions of packages to the Beowulf ones.
Both Firefox-esr and Chromium have a version in Beowulf which appears to be older, so I forced the versions.
Also devuan-baseconf. Trying to force the version of that crashed Synaptic.
So I had to sort sources.list and removed the backports which don't seem ready yet!

I removed lots of packages which were not in Beowulf. The Beowulf stuff gets reported as "testing".
The others are reported as "now", which I guess means that it is not in the selected repositories.
Packages which I removed include :-
php7.0
ruby 2.1 & 2.2
leafpad
an older WordPress theme from ASCII
webkit-image-qt possibly used by the old version of Claws-mail and is now replaced by Dillo.
as well as numerous libraries and old versions of things, which had no dependencies.

After the version forcing and the removals I was left with gksu and some libraries on which it is dependent,
as well as keeping one old kernel, just in case it was needed.

$ aptitude search ~i -F"%p# %v# %t#"|grep -v testing | awk -e '{print $1,"   \t\t" $2,"\t" $3}' -
gksu    		2.0.2-9+b1 	now
libgksu2-0    		2.0.13~pre1-9+b1 	now
libgnome-keyring-common    		3.12.0-1 	now
libgnome-keyring0    		3.12.0-1+b2 	now
libgtop-2.0-10    		2.34.2-1 	now
libssl1.0.0    		1.0.2d-1 	now
linux-image-4.18.0-0.bpo.1-amd64    		4.18.6-1~bpo9+1 	now

Things are now largely running normally.

Geoff