There was a tutorial here (credited below) earlier talking of how to make mouse cursors consistent across all of your applications. There is justification for it to exist, but I don't believe it is the easiest method in the long-run, considering Gnome and MATE keep two separate mouse cursor settings. Using some of the information provided in that thread, I believe there is an easier way, with a little bit of setup.
Terminal to the rescue
...So this is using symbolic links. Again. If symlink is a familiar term, it's probably because they're the easiest means of having a background image apply across multiple DEs. and the same trick is being used in this case to use the same cursor everywhere.
This method means every time one desires the change the cursor, they must do
sudo update-alternatives --config x-cursor-theme. But after using Linux systems for some time, using the terminal, despite how user-unfriendly it is in comparison to a GUI app seems to be the best way of doing things in some circumstances. So here's how to make the specification in update-alternatives apply everywhere;
sudo mkdir /usr/share/icons/x-cursor-theme
# ^ Assuming this is what you call the directory; Name it whatever you wish.
sudo ln -s /etc/alternatives/x-cursor-theme /usr/share/icons/x-cursor-theme/index.theme
# ^ Using the directory made, take the theme index from /etc/alternatives
# and use it as the index for theme "x-cursor-theme"
gsettings set org.gnome.desktop.interface cursor-theme x-cursor-theme
gsettings set org.mate.peripherals-mouse cursor-theme x-cursor-theme
# ^ Use the new theme, named "x-cursor-theme"
gsettings set org.gnome.desktop.interface cursor-size 18
gsettings set org.mate.peripherals-mouse cursor-size 18
# ^ Set a consistent cursor size. The value specified will appear later below.
# ^ See below about this.
For this particular file, it is a special hidden file which can be made to tell X what cursor is to be used. Not entirely sure if it's necessary but I'm throwing it in anyway. In
That should do it. If desired, also edit
/etc/gtk-3.0/settings.ini to add the following;
gtk-cursor-theme-name = x-cursor-theme
gtk-cursor-theme-size = 18
After, since it seems this file is exactly the same give or take a few lines compared to
/etc/gtk-2.0/gtkrc, this can be done;
sudo rm -rf /etc/gtk-2.0/gtkrc
sudo ln -s /etc/gtk-3.0/settings.ini /etc/gtk-2.0/gtkrc
Why do we even have to do this? I don't get it myself, since Cinnamon does just fine with cursors, as does KDE. Also, this is for a single user; Multi-user environments may have disagreements on which theme to use, so I'll have a play with trying to individualize these settings, but undoubtedly it will involve the use of symlinks and variable values.