The newest Ubuntu MATE 22.04 LTS is released. It works and looks great. 
Bugs
There are some bugs out of our control - for me the most horrible bugs are the following:
- https://bugs.launchpad.net/ubuntu/+source/vte2.91/+bug/1922276
- https://bugs.launchpad.net/ubuntu/+source/readline/+bug/1926256
To fix the 1922276 bug one can use 20.04 LTS's VTE library from my PPA as follows:
sudo add-apt-repository ppa:nrbrtx/vte
sudo apt-get update
sudo apt-get dist-upgrade
and then be able to to select all terminal output with full scroll-back in MATE Terminal and other VTE-based terminals as it is expected.
Note: if you have any problems with the packages from above PPA, you can downgrade the packages by running sudo apt-get install ppa-purge; sudo ppa-purge ppa:nrbrtx/vte and continue to use VTE-based terminals with bug 1922276.
To fix the 1926256 bug one can use the following one liner for current user
echo "set enable-bracketed-paste Off" > ~/.inputrc
and then enjoy traditional copy-paste behavior in the terminal.
Three other bugs are 1922414, 1955135 and 1955136. They break normal Xsession initialization and fill the ~/.xsession-errors with the following error messages :
/etc/X11/Xsession.d/30x11-common_xresources: line 16: has_option: command not found /etc/X11/Xsession.d/75dbus_dbus-launch: line 9: has_option: command not found /etc/X11/Xsession.d/90x11-common_ssh-agent: line 9: has_option: command not found
Local fix for for these 3 bugs can be applied by executing long command below to re-add missing has_option function:
cat <<\EOF | sudo tee /etc/X11/Xsession.d/20x11-add-hasoption
# temporary fix for LP# 1922414, 1955135 and 1955136 bugs
# read OPTIONFILE
OPTIONS=$(cat "$OPTIONFILE") || true
has_option() {
if [ "${OPTIONS#*
$1}" != "$OPTIONS" ]; then
return 0
else
return 1
fi
}
EOF
and then reboot. This will allow ssh-agent to start and other necessary fixes.
Note: if you have any additional issues caused by adding above file - please feel free to remove it by sudo rm /etc/X11/Xsession.d/20x11-add-hasoption and inform me about this problem.
Workarounds and fixes
Libssl1.1
Some applications are not yet ready for work with new set of packages which is shipped with 22.04 LTS. For example it is known that libssl1.1 is now removed in favor of OpenSSL 3.0. To fix this issue one can add my PPA to the system using below commands:
sudo add-apt-repository ppa:nrbrtx/libssl1
sudo apt-get update
and then install single libssl1.1 package by sudo apt-get install libssl1.1 to satisfy dependencies of some application.
Note: above is not an issue for RStudio anymore, they have released correctly packaged version for Jammy.
Traditional Themes
It is already known that there is some disappointment about new default Yaru-MATE themes.
This is really fixable (thanks to lah7!) by using theme packages from special PPA as follows:
sudo add-apt-repository ppa:lah7/ambiant-mate
sudo apt-get update
sudo apt-get install ambiant-mate-colours-all
and then select needed theme in MATE Control Center → Appearance.
Note: one can also install mate-themes package to get traditional MATE themes installed.
Non-snap web-browsers
Ubuntu MATE Welcome Software Boutique allows one to install Firefox ESR or other deb-packaged browsers at one click.