Event:UNIT TARGET CHANGED

Triggered when a new target is selected or deselected (either by clicking on a monster or NPC, pressing the alt key or escape to cancel your selection).
Arguments
:;arg1
::UnitId of the Unit that changed its selection ("player")
:;arg2
::Unique identifier of the selected target. 0 Essentially means he cancelled his last target and has no current target or that he is targeting himself. If the cancellation is due to distance/visibility change, then the return value can be anything between 0 and X (typically I've seen values between 1 and 3000). MonsterID values are much, much higher than the values of cancellation, so we can use that to determine which it is.
:;arg3
::Unknown integer (0)
:;arg4
::Apparently, the name of the last player that spoke.
::Example:
 function Addon_TargetChanged(arg1,arg2)
 if(arg2 == 0) then
 --UnitID(arg1) doesn't have any target or is targeting himself.
 elseif(arg2 < 10000) --value limit needs testing, this is what I would use to be safe from getting mixed into the unique identifier.
 --UnitID(arg1) doesn't have any target due to target disappearing from view or dying (and thus being deselected).
 else
 --UnitID(arg1) changed it's target to a monster with ID (arg2).
 end
 end
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