Better way of setting mouse pointer/cursor theme and size

[billyswong]

Continuation on discussion in linuxmint/mint22-beta#39

Currently, setting mouse cursor theme and size is annoying. There are GUI dialogs for them in all DEs supported by Linux Mint. Although their locations are different among Cinnamon, Mate and Xfce, it is still tolerable as they are different DEs. But the problem is, setting the theme and size within the GUI dialogs provided by these DEs are not the end of story.

The sad reality is a user also need to know the quirk and run extra terminal commands to complete the settings for many applications not based on GTK. For terminal commands I mean things such as
sudo update-alternatives --config x-cursor-theme
and
sudo sh -c 'echo "export XCURSOR_SIZE=48" > /etc/profile.d/qt_mouse_pointer_size.sh'
Command 1 is written in Linux Mint release note while the command 2 isn't. But no matter they are written in release note or not, such annoyance shouldn't happen in the first place. A user shouldn't need to do both GUI and CLI for conceptually one setting.

I don't know which party is responsible for this mess, but hopefully we can create a fix for Linux Mint. Even if the solution ends up only works for Cinnamon, it is still better than nothing.