The standard reference for "pointer warping" for Tk has been the "usage FAQ" [http://www.hobbs.wservice.com/tcl/faqs/tk/tkfaq.html].
It briefly mentions that pointer warping is a bad idea ([don't do that]), supplies source for an extension
which implements warping, and also points to [[fill in the details here ...]], with its implementation of the same as ...  The FAQ doesn't seem to be current ...

As "[Changes in Tcl/Tk 8.3]" hints, release 8.3's [event] command builds in pointer warping.

Here is a simple example of pointer warping:

event generate . <Motion> -warp 1 -x 50 -y 50.

(Move the cursor to the '.' window, inset 50 pixels from top left corner)

Among the legitimate uses of pointer warping are test automations, including [Android], and for pedagogic purposes (Android can also
help build demonstrations).