highlight the cursor whenever the window scrolls

 Whenever the window scrolls a light will shine on top of your cursor so you
 know where it is.
 .
 Customizations:
 .
  * the appearance of the beacon;
  * the duration;
  * when the beacon should blink at all;
  * prevent the beacon from blinking only on specific situations;
  * push the mark for you whenever point moves a long distance.