I often play as a healer. My favorite way to heal is to mouse over a friendly unit frame or 3D model and press the hotkey of the spell I wish to cast. I do this via "mouseover" macros.
Example macro:
/cast [@mouseover,help][] Penance
This macro says: "Cast on a friendly target my mouse is over. If none, try to cast using the default targeting mechanism." This allows me to keep my mouse over unit frames and hit buttons rather than needing to click at all. I find it quick, easy, and intuitive.
However, doing this means I need to have a whole lot of macros. There aren't all that many macros available (18 per-character macros) so it'd be nice if I didn't have to clog up my healer macro slots with pretty much every healing spell I know.
Is there a way to do this mouseover behavior without a macro?
Best Answer
The only other way to do this without a macro is through the use of an addon.
Clique is probably the most well known such mod - it essentially allows you to bind spells conditionally based upon the frame which you're currently moused over.
It's extremely popular with healers.