Is there a 3rd party app or combination of system settings and scripts that dims a secondary monitor until focus is brought to a window displayed on it? I like having multiple monitors but I would work better if there were a strong contrast between the two, where the contrast would invert based on which monitor had focus. (I can and do manually adjust the brightness when I know I won't need anything on the secondary monitor for awhile).
Running El Capitan with primary of a Thunderbolt display and secondary of a Macbook Pro.
I have looked at questions such as Show a screensaver on a secondary display and Adjust brightness of secondary display and have a sense that some of the tools might, with a additional scripting, get me close to what I'm looking for, but I am hoping someone has already solved this specific issue.