Describe the feature

When the player is out of combat (or not targeted if Target frame?), the unit frame would be faded out. It would be nice to unfade when the player hovers over that unit frame as well.

Describe the implementation

This option could be set in the individual unit frames section with options for 'Alpha' for standard opacity, and 'Out of Combat Opacity. Shadowed Unit Frames has the 'Combat Fader' which lets users set the alpha when in combat, and when inactive.