ShowCursorTracker

ShowCursorTracker is an option for Cell which specifies whether an elliptical spot should appear momentarily to guide the eye if the cursor position jumps.

The default setting is ShowCursorTracker -> True.

Line breaking is normally set up so that small changes to expressions in input cells rarely cause large-scale reformatting; the cursor tracker appears whenever reformatting is required that makes the cursor position jump.

The cursor tracker is intended to be sufficiently eye-catching to make the low-level human visual system cause an immediate shift in gaze.

See The Mathematica Book: Section 2.10.11.

See also: DelimiterFlashTime, ShowAutoStyles.