My interpretation is that it sets the limit for how far dims can be off screen. .2 means up to 20% off screen, Creo ignores it and leaves it there. Beyond 20%, it snaps it back on screen. If set to zero, however, Creo does nothing to bring dims back on screen regardless of how far out they are.
That said, I've had this set at 0.01 for years and my angle dims behave just like described above. Perhaps this only applies to linear dims? I don't recall having to find them as often.
I can't help but wonder why this setting exists.