This very small and simple addon makes you able to set your focus by shift clicking a unit frame (your target, a raid member etc) or by shift clicking a model directly. (Just as you would target something normally)

Should work with most (if not all) unitframes addons such as Pitbull or Grid. Should also be no problem to use this addon together Clique, Click2Heal or any other click addons as long as you don't bind shift leftclick to something else.

There are zero configuration at the moment, as there is hardly anything to configure. If you still would want to change the set focus key combination you can edit the first two lines of the lua code, it's pretty self explanatory.