Which application changed Mac OS X [Option]+[D] keybinding When I press Option+D key in OS X, the current application loses focus. And if I press it again, the current window gets focus back.

How do I know which application bind that or how to avoid it. I checked the shortcuts in System Preferences and there isn't anything like Option+D keybinding.

System version:

ProductName:  Mac OS X
ProductVersion: 10.11.4
BuildVersion:   15E65


This annoys me so much.
create a new user and login as that new user to see whether it works normally.

In my case, it works normally. Then check login items of the current user: Preferences > Users &amp; Groups > Login items. Then remove unuseful items and relogin, remember to uncheck reopen windows when relogin.

Then, everything works normally. Thanks Nunzy in #MacOSX channel!

Thank you so much!!!