Unit Hit Point Bars
 

During some games, in combat, I can see hit point bars for each troop in combat, both mine and enemy. The bar seems to represent the HP's of one unit within the stack (not the total remaining health of the stack).

It's on a hero-to-hero basis I don't know why I sometimes have them and sometimes not. I keep thinking it's a benefit of a particular skill. I also thought maybe I'm hitting an undocumented hot key.

Does anyone know what I'm talking about?

I noticed the same and thought about it for a while. Then i realized it only happens when I alt-tab.

Try Alt.

The alt key toggles the hp bar.

Yup. you are correct sir.

I wonder how many other undocumented hotkeys are out there ...