Y PPA Manager requires Mir, and fails to start

[Norbert]

Steps to reproduce:
1. Launch Ubuntu 16.04 LTS with MATE DE
2. Install y-ppa-manager

add-apt-repository ppa:webupd8team/y-ppa-manager -y
apt-get update
apt-get install y-ppa-manager -y

3. Launch Y PPA Manager from terminal with y-pkexec

Expected results:
Y PPA Manager starts and works normally.

Actual results:

$ y-pkexec
Gtk-Message: Failed to load module "gail"
Gtk-Message: Failed to load module "atk-bridge"
Failed to connect to Mir: Failed to connect to server socket: No such file or directory
Unable to init server: Could not connect: Connection refused

(Y PPA Manager:13342): Gtk-WARNING **: cannot open display:

$ gksu y-ppa-manager
Gtk-Message: Failed to load module "gail"
Gtk-Message: Failed to load module "atk-bridge"
No protocol specified
Failed to connect to Mir: Failed to connect to server socket: No such file or directory
Unable to init server: Could not connect: Connection refused

(Y PPA Manager:14206): Gtk-WARNING **: cannot open display: :7.0

$ gksu y-pkexec
Gtk-Message: Failed to load module "gail"
Gtk-Message: Failed to load module "atk-bridge"
Failed to connect to Mir: Failed to connect to server socket: No such file or directory
Unable to init server: Could not connect: Connection refused

(Y PPA Manager:14674): Gtk-WARNING **: cannot open display:

Note: I get this bug on the LTSP fat client. Here are local sudo account and root account. But other graphical pkexec'ed and gksu applications such as Synaptic start normally here.

Here is my environment:

$ export
declare -x CLUTTER_BACKEND="x11"
declare -x COLORTERM="mate-terminal"
declare -x COMPIZ_CONFIG_PROFILE="mate"
declare -x DBUS_SESSION_BUS_ADDRESS="unix:abstract=/tmp/dbus-8fJc0OtwFS,guid=365d29b346801c08b011bba25a166abd"
declare -x DEFAULTS_PATH="/usr/share/gconf/mate.default.path"
declare -x DESKTOP_SESSION="mate"
declare -x DISPLAY=":7.0"
declare -x GTK_MODULES="gail:atk-bridge:canberra-gtk-module:topmenu-gtk-module"
declare -x GTK_OVERLAY_SCROLLING="0"
declare -x HOME="/home/ltsp157"
declare -x ICEAUTHORITY="/var/run/ldm-xauth-TKxGi4qxn/ICEauthority"
declare -x LANG="en_US.UTF-8"
declare -x LESSCLOSE="/usr/bin/lesspipe %s %s"
declare -x LESSOPEN="| /usr/bin/lesspipe %s"
declare -x LIBVIRT_DEFAULT_URI="qemu:///system"
declare -x LOGNAME="ltsp157"
declare -x LS_COLORS="rs=0:di=01;34:ln=01;36:mh=00:pi=40;33:so=01;35:do=01;35:bd=40;33;01:cd=40;33;01:or=40;31;01:mi=00:su=37;41:sg=30;43:ca=30;41:tw=30;42:ow=34;42:st=37;44:ex=01;32:*.tar=01;31:*.tgz=01;31:*.arc=01;31:*.arj=01;31:*.taz=01;31:*.lha=01;31:*.lz4=01;31:*.lzh=01;31:*.lzma=01;31:*.tlz=01;31:*.txz=01;31:*.tzo=01;31:*.t7z=01;31:*.zip=01;31:*.z=01;31:*.Z=01;31:*.dz=01;31:*.gz=01;31:*.lrz=01;31:*.lz=01;31:*.lzo=01;31:*.xz=01;31:*.bz2=01;31:*.bz=01;31:*.tbz=01;31:*.tbz2=01;31:*.tz=01;31:*.deb=01;31:*.rpm=01;31:*.jar=01;31:*.war=01;31:*.ear=01;31:*.sar=01;31:*.rar=01;31:*.alz=01;31:*.ace=01;31:*.zoo=01;31:*.cpio=01;31:*.7z=01;31:*.rz=01;31:*.cab=01;31:*.jpg=01;35:*.jpeg=01;35:*.gif=01;35:*.bmp=01;35:*.pbm=01;35:*.pgm=01;35:*.ppm=01;35:*.tga=01;35:*.xbm=01;35:*.xpm=01;35:*.tif=01;35:*.tiff=01;35:*.png=01;35:*.svg=01;35:*.svgz=01;35:*.mng=01;35:*.pcx=01;35:*.mov=01;35:*.mpg=01;35:*.mpeg=01;35:*.m2v=01;35:*.mkv=01;35:*.webm=01;35:*.ogm=01;35:*.mp4=01;35:*.m4v=01;35:*.mp4v=01;35:*.vob=01;35:*.qt=01;35:*.nuv=01;35:*.wmv=01;35:*.asf=01;35:*.rm=01;35:*.rmvb=01;35:*.flc=01;35:*.avi=01;35:*.fli=01;35:*.flv=01;35:*.gl=01;35:*.dl=01;35:*.xcf=01;35:*.xwd=01;35:*.yuv=01;35:*.cgm=01;35:*.emf=01;35:*.ogv=01;35:*.ogx=01;35:*.aac=00;36:*.au=00;36:*.flac=00;36:*.m4a=00;36:*.mid=00;36:*.midi=00;36:*.mka=00;36:*.mp3=00;36:*.mpc=00;36:*.ogg=00;36:*.ra=00;36:*.wav=00;36:*.oga=00;36:*.opus=00;36:*.spx=00;36:*.xspf=00;36:"
declare -x LTSP_CLIENT="10.3.165.230"
declare -x LTSP_CLIENT_HOSTNAME="ltsp230"
declare -x LTSP_CLIENT_MAC="00:22:4D:AD:80:1D"
declare -x LTSP_FATCLIENT="True"
declare -x MAIL="/var/mail/ltsp157"
declare -x MANDATORY_PATH="/usr/share/gconf/mate.mandatory.path"
declare -x MATE_DESKTOP_SESSION_ID="this-is-deprecated"
declare -x OLDPWD
declare -x PATH="/home/ltsp157/bin:/home/ltsp157/.local/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games"
declare -x PWD="/home/ltsp157"
declare -x QT_ACCESSIBILITY="1"
declare -x QT_LINUX_ACCESSIBILITY_ALWAYS_ON="1"
declare -x QT_STYLE_OVERRIDE="gtk"
declare -x SESSION_MANAGER="local/ltsp230:@/tmp/.ICE-unix/1689,unix/ltsp230:/tmp/.ICE-unix/1689"
declare -x SHELL="/bin/bash"
declare -x SHLVL="2"
declare -x SSH_AGENT_PID="1815"
declare -x SSH_AUTH_SOCK="/run/user/1158/keyring/ssh"
declare -x SYSTEMD_PAGER=""
declare -x TERM="xterm"
declare -x USER="ltsp157"
declare -x WINDOWID="58720288"
declare -x XAUTHORITY="/var/run/ldm-xauth-TKxGi4qxn/Xauthority"
declare -x XDG_CONFIG_DIRS="/etc/xdg/xdg-mate:/etc/xdg"
declare -x XDG_CURRENT_DESKTOP="MATE"
declare -x XDG_DATA_DIRS="/usr/share/mate:/usr/share/mate:/usr/local/share/:/usr/share/"
declare -x XDG_RUNTIME_DIR="/run/user/1158"
declare -x XDG_SEAT="seat0"
declare -x XDG_SESSION_ID="c1"
declare -x XDG_VTNR="7"

[Launchpad Janitor (janitor)]

[Expired for Y PPA Manager because there has been no activity for 60 days.]