set-mouse-pixel-position

set-mouse-pixel-position is a built-in function in `C source code'.

(set-mouse-pixel-position FRAME X Y)

Move the mouse pointer to pixel position (X,Y) in FRAME.
The position is given in pixels, where (0, 0) is the upper-left corner
of the frame, X is the horizontal offset, and Y is the vertical offset.

Note, this is a no-op for an X frame that is not visible.
If you have just created a frame, you must wait for it to become visible
before calling this function on it, like this.
(while (not (frame-visible-p frame)) (sleep-for .5))