I've tried a bit of dual boxing before and i'm now returning with tri boxing 3 elemental shammies. However, i see a lot of videos like this:

http://www.youtube.com/watch?v=Cz3HaGzIg34

As you can see, at 1:28 they use some sort of command to make each of the shammies split up into a line.

A) Is there any reason for doing this?
B) How are they doing this?


Thanks,
Xelem