lubuntu 18.04.2 qa-test install: virtual machine on sony vaio ultrabook (i5-9400u, 4gb, intel haswell-ULT); host is lubuntu 19.04

I didn't use `vim` to change sources, but found I could achieve equivalent with synaptic [package manager] which was pre-installed on Lubuntu 18.04; settings->repositories  and selecting using drop down australia->ftp.iinet.net.au.  i made no other changes
(note: mine wasn't identical, I don't recall adding -backports & had 'main universe multiverse restricted' for bionic, -updates, -security)

i `sudo vi /etc/update-manager/release-upgrades` ("=normal"); `sudo apt update` (probably pointless but ..)

`do-release-upgrade -p`

..
6 installed packages are no longer supported by Canonical.  You can ..
..
on questions I used default (eg. lightdm as it was highlighted, not sddm or what I assume most users would do), package-maintainers-version, (y) remove obselete packages (probabe some users are likely to choose no for this), reboot (y)

login  (after reboot), brief explore & it's LXQt desktop, reboot(vm) & again login and [still] looks correct

            .-/+oossssoo+/-.               guiverc@lubu-sru-test 
        `:+ssssssssssssssssss+:`           ---------------------                                                                                              
      -+ssssssssssssssssssyyssss+-         OS: Ubuntu 18.10 x86_64                                                                                            
    .ossssssssssssssssssdMMMNysssso.       Host: VirtualBox 1.2                                                                                               
   /ssssssssssshdmmNNmmyNMMMMhssssss/      Kernel: 4.18.0-15-generic                                                                                          
  +ssssssssshmydMMMMMMMNddddyssssssss+     Uptime: 2 mins                                                                                                     
 /sssssssshNMMMyhhyyyyhmNMMMNhssssssss/    Packages: 2188 (dpkg)                                                                                              
.ssssssssdMMMNhsssssssssshNMMMdssssssss.   Shell: bash 4.4.19                                                                                                 
+sssshhhyNMMNyssssssssssssyNMMMysssssss+   Resolution: 800x600                                                                                                
ossyNMMMNyMMhsssssssssssssshmmmhssssssso   DE: LXQt                                                                                                           
ossyNMMMNyMMhsssssssssssssshmmmhssssssso   WM: Openbox                                                                                                        
+sssshhhyNMMNyssssssssssssyNMMMysssssss+   Theme: Arc-Darker [GTK3]                                                                                           
.ssssssssdMMMNhsssssssssshNMMMdssssssss.   Icons: Adwaita [GTK3]                                                                                              
 /sssssssshNMMMyhhyyyyhdNMMMNhssssssss/    Terminal: qterminal                                                                                                
  +sssssssssdmydMMMMMMMMddddyssssssss+     CPU: Intel i5-4200U (1) @ 2.294GHz                                                                                 
   /ssssssssssshdmNNNNmyNMMMMhssssss/      GPU: VMware SVGA II Adapter                                                                                        
    .ossssssssssssssssssdMMMNysssso.       Memory: 357MiB / 985MiB                                                                                            
      -+sssssssssssssssssyyyssss+-                                                                                                                            
        `:+ssssssssssssssssss+:`                                                                                                                              
            .-/+oossssoo+/-.