New mouse cursor doesn't appear in list sudo update-alternatives --config x-cursor-theme

I believe you have to move your theme to the /usr/share/icons directory for it to work.

Also you have to locate the index.theme (or any .theme file) of the theme you want to install and add it to update-alternatives using the --install option.

Let's take as example the theme ComixCursors-LH-White-Small ( a left-handed cursor theme from the package comixcursors-lefthanded ). Its index.theme file looks like

[Icon Theme]
Name = Comix Cursor LH White Small Bold
Comment = The left-handed Comix Cursors - White Small Bold
Example = default

but it should have an Inherits line equal to the directory in /usr/share/icons in which the theme is saved, otherwise it won't work. So add

Inherits = ComixCursors-LH-White-Small

Now tell update-alternatives about your new theme

sudo update-alternatives --install /usr/share/icons/default/index.theme x-cursor-theme /usr/share/icons/ComixCursors-LH-White-Small/index.theme 91

where you should change the second last parameter to the index.theme of your theme. If you did this correctly

sudo update-alternatives --config x-cursor-theme

should display your new theme, and after logging out and in, your new theme should be applied.

Alternatives available for update-alternatives need to be set up prior to use. This is normaly done by the package scripts. You can add your theme as an alternative like so:

update-alternatives --install /usr/share/icons/default/index.theme x-icon-theme /usr/share/icons/$YOURTHEME/cursor.theme 9999

or you can just link your file to /usr/share/icons/default/index.theme and forget about the alternatives system.