actually it can be VERY usefull to save Action Button !

Was Dual Boxing Priest and Warrior as a Warrior for my main screen and made macro to target my Warrior and heal him but when playing with other ppl and friends you can't heal them -_- or you have to drop one in your bar and click it or do a other macro which is annoying my having a Mouse Over Heal I can just heal my Warrior Bubble and everything and don't have to mess with 10000 macro