Why spend the time writing an addon when a mouse-click would suffice?
I see your point, but it would make it alot easier since I get them all the time when Mining, so if right when I get 10 of a certain kind it would just automatically change it to Eternal.
I do not believe an addon can do that for you automatically. The game requires a hardware event for things like that. I suppose it could pop up a window/button for you when you collect enough so you can click to do it, though.
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"You'd be surprised how many people violate this simple principle every day of their lives and try to fit square pegs into round holes, ignoring the clear reality that Things Are As They Are." -Benjamin Hoff, The Tao of Pooh