I reverted to the correct behaviour by
cd /home/david/DisplayBug-Jul7-2018
sudo dpkg -i \ libgbm1_17.2.8-0ubuntu0~16.04.1_amd64.deb \ libwayland-egl1-mesa_17.2.8-0ubuntu0~16.04.1_amd64.deb \ libegl1-mesa_17.2.8-0ubuntu0~16.04.1_amd64.deb \ libgl1-mesa-dri_17.2.8-0ubuntu0~16.04.1_amd64.deb \ libgl1-mesa-dri_17.2.8-0ubuntu0~16.04.1_i386.deb \ mesa-vdpau-drivers_17.2.8-0ubuntu0~16.04.1_amd64.deb
sudo apt-mark hold \ libegl1-mesa \ libgbm1 \ libgl1-mesa-dri \ libwayland-egl1-mesa \ mesa-vdpau-drivers
I reverted to the correct behaviour by
cd /home/david/ DisplayBug- Jul7-2018
sudo dpkg -i \ 17.2.8- 0ubuntu0~ 16.04.1_ amd64.deb \ egl1-mesa_ 17.2.8- 0ubuntu0~ 16.04.1_ amd64.deb \ mesa_17. 2.8-0ubuntu0~ 16.04.1_ amd64.deb \ mesa-dri_ 17.2.8- 0ubuntu0~ 16.04.1_ amd64.deb \ mesa-dri_ 17.2.8- 0ubuntu0~ 16.04.1_ i386.deb \ drivers_ 17.2.8- 0ubuntu0~ 16.04.1_ amd64.deb
libgbm1_
libwayland-
libegl1-
libgl1-
libgl1-
mesa-vdpau-
sudo apt-mark hold \ egl1-mesa \ vdpau-drivers
libegl1-mesa \
libgbm1 \
libgl1-mesa-dri \
libwayland-
mesa-