Wayland is designed to not allow elevated (sudo -H, gksu ...) permissions with GUI application programs. It is a good idea to do such tasks with command line tools. But there are workarounds, if you have a GUI tool, that works well for you and needs elevated permissions.
Temporary access for root to the Wayland desktop
1. There is a workaround to allow graphical application programs owned by other users than the logged in user in Wayland,
2. 'gksu' and 'gksudo' are not bundled with standard Ubuntu. Do not use them. Instead you can use
3. It is a good idea to prevent graphical application programs owned by other users than the logged in user afterwards,
Links to AskUbuntu
Several ways to solve this problem are shown at the following link to AskUbuntu,
The next link shows the particular method, that is described here,
Icon file for the desktop file 'gks.desktop' and the shellscript 'gks'
You can download this file, gks.svg. When you arrive at the attachment page, right click on the download link and select save link as ....
The md5sum is
$ md5sum gks.svg 7c955ff11d73a996445be99306b83fac gks.svg
The three files 'gks', 'gks.desktop' and 'gks.svg'
You can also download this file, gks-files.tar.gz, with the 3 files that are used for this purpose,
desktop file gks.desktop
icon file gks.svg
The md5sum is
$ md5sum gks-files.tar.gz 299e10e42a843ec197ca223179ef1f50 gks-files.tar.gz
and the files are
$ tar -tvf gks-files.tar.gz -rwxr-xr-x sudodus/sudodus 522 2017-10-31 18:45 gks -rwxr-xr-x sudodus/sudodus 384 2017-10-31 18:44 gks.desktop -rw-rw-r-- sudodus/sudodus 5633 2017-10-31 18:09 gks.svg
You can extract the files with
tar -xvf gks-files.tar.gz
Copy the [extracted or copied & pasted] files to the following locations,
sudo cp gks /usr/bin sudo cp gks.desktop /usr/share/applications/ sudo cp gks.svg /usr/share/icons
Logout/login or reboot, and there should be a working desktop icon, that works via the Gnome Shell menu. It will work directly with the shellscript gks from Alt-F2 and from a terminal window too,
gks gedit myfile.txt