ah, the xhost command still works, even though on wayland; I didn't expect that. 
executing the below xhost on the command line worked, so I assume the creation of the xhost.desktop file (described below) will indeed do the trick.
thanks! 

On Tue, Oct 24, 2017 at 01:23:12PM -0000, jervin wrote:
> sudo gedit fstab
> Invalid MIT-MAGIC-COOKIE-1 keyUnable to init server: Could not connect: Connection refused
> 
> (gedit:17700): Gtk-WARNING **: cannot open display: :0
> 
> -- 
> You received this bug notification because you are subscribed to a
> duplicate bug report (1726742).
> https://bugs.launchpad.net/bugs/1712089
> 
> Title:
>   Invalid MIT-MAGIC-COOKIE-1 keyUnable to init server: Could not
>   connect: Connection refused
> 
> Status in synaptic package in Ubuntu:
>   Triaged
> 
> Bug description:
>   List of pkexec'ed applications is located in bug 1713313.
>   List of packages which use su-to-root and gksu/gksudo is located in bug 1713311.
> 
>   -----------------------------------------------------------------------------
>   pkexec'ed applications may be healed with "xhost +si:localuser:root" placed in XDG autostart as follows:
> 
>   cat <<EOF | sudo tee /etc/xdg/autostart/xhost.desktop
>   [Desktop Entry]
>   Name=xhost
>   Comment=Fix graphical root applications
>   Exec="xhost +si:localuser:root"
>   Terminal=false
>   Type=Application
>   EOF
> 
>   -----------------------------------------------------------------------------
> 
>   Posting here what gnome says about porting to wayland, and their
>   tests:
> 
>   GNOME Applications under Wayland
>   GTK+ has a Wayland backend. If it was enabled at compile-time, you can run a GTK+ application under Wayland simply by:
> 
>   GDK_BACKEND=wayland gnome-calculator
>   Applications that use Clutter or clutter-gtk also need the Clutter Wayland backend enabled:
> 
>   GDK_BACKEND=wayland CLUTTER_BACKEND=wayland cheese
> 
>   https://wiki.gnome.org/Initiatives/Wayland/Applications
> 
>   ======> so hope the settings are well set at compile time; maybe a
>   rebuilt to get sure all apps are ok.
> 
>   ********************************************************************************************************************************************
> 
>   With the today packages upgrade, switching from X11 to wayland,
>   synaptic refuse to load/open:
> 
>   from the icon into the dash-to-dock, nothing happen
>   from the terminal:
> 
>   sudo synaptic
>   [sudo] password for oem:
>   Invalid MIT-MAGIC-COOKIE-1 keyUnable to init server: Could not connect: Connection refused
> 
>   (synaptic:2154): Gtk-WARNING **: cannot open display: :0
> 
>   Previous days already have switching some packages to wayland, but
>   synaptic was still working. Its only with the today upgrades, after a
>   cold reboot, that synaptic gui is broken.
> 
>   Today possibly sources problem:
> 
>   Unpacking console-setup-linux (1.142ubuntu7) over (1.142ubuntu5) ...
> 
>   Unpacking console-setup (1.142ubuntu7) over (1.142ubuntu5) ...
> 
>   Unpacking keyboard-configuration (1.142ubuntu7) over (1.142ubuntu5)
>   ...
> 
>   Unpacking gnome-session-bin (3.24.1-0ubuntu22) over (3.24.1-0ubuntu21)
>   ...
> 
>   Unpacking gdm3 (3.25.90.1-0ubuntu2) over (3.25.90.1-0ubuntu1) ...
> 
>   Unpacking libgdm1 (3.25.90.1-0ubuntu2) over (3.25.90.1-0ubuntu1) ...
> 
>   Unpacking gir1.2-gdm-1.0 (3.25.90.1-0ubuntu2) over
>   (3.25.90.1-0ubuntu1) ...
> 
>   Unpacking ubuntu-session (3.24.1-0ubuntu22) over (3.24.1-0ubuntu21)
>   ...
> 
>   Unpacking gnome-session (3.24.1-0ubuntu22) over (3.24.1-0ubuntu21) ...
>   ...
>   Unpacking gnome-session-common (3.24.1-0ubuntu22) over (3.24.1-0ubuntu21) ...
>   Setting up keyboard-configuration (1.142ubuntu7) ...
> 
>   ProblemType: Bug
>   DistroRelease: Ubuntu 17.10
>   Package: synaptic 0.84.2
>   ProcVersionSignature: Ubuntu 4.12.0-12.13-generic 4.12.8
>   Uname: Linux 4.12.0-12-generic x86_64
>   ApportVersion: 2.20.6-0ubuntu6
>   Architecture: amd64
>   CurrentDesktop: GNOME
>   Date: Mon Aug 21 16:21:47 2017
>   EcryptfsInUse: Yes
>   SourcePackage: synaptic
>   UpgradeStatus: No upgrade log present (probably fresh install)
> 
> To manage notifications about this bug go to:
> https://bugs.launchpad.net/ubuntu/+source/synaptic/+bug/1712089/+subscriptions