[Grimsin]

this might be possible but it would be far from lightweight. In order to make those buttons work they would have to be written in secure code so that they still worked in combat. Also a huge library would have to be written to handle that bar knowing what spells to put on the buttons based on what you are targeting and what class you are, what level you are and what spec and everything else.

Also the tricky part would be making the bar follow moving targets, i would look at the nameplate system and maybe think about tying this into the nameplate system or at least attempt to use the methods found there for keeping the bar over the initial target.