You can change the shape of the mouse pointer using the following example by KaiGrossjohann:
(setq x-pointer-shape x-pointer-top-left-arrow) (set-mouse-color "black")
Setting the mouse-color is believed to be necessary to “refresh” the pointer shape.
All the shapes are predefined by X in GIT:term/x-win.el.
If you are trying to make the mouse unobtrusive, MouseAvoidance can move the mouse out of your way.
The value of x-pointer-shape does not always correspond to the mouse pointer shape while the pointer is located in an emacs windows. Default cursor shapes and colors may also be used. For default cursor shapes, X windows looks at the Xcursor.theme value (e.g., in ~/.Xdefaults). See ‘man xcursor’ for more details.