Modify or Add new Next Target

[Olympicus]

Hi everyone, im looking for some tips about how to change the next target "range" in client
or if possible to make something like this

 

[default_npc]

nwindow

 

[Olympicus]

nwindow

thanks for the advice !!!
maybe one of this? i think retail next target dont have more than 400 range

 

[LightFusion]

nwindow.dll