I will often have my companion as the focus and have mapped the Focus Mod key to mouse button 5 (Logitech mouse withnsetpoint running as admin so it works in game) but it doesn't always work correctly. I can hold the button down and chain cast heals with a few of them going to me instead of my companion. Without letting go of button five, I can cast four heals and at least one goes to me instead.
I've tried other mouse buttons and at least on key ( '[' as I recall) and had the same results. Is anyone else seeing this? Just wondering if I should bug it or try some other keyboard/mouse combo.