In past versions of OSX you can toggle between mirror displays (if you have more than one monitor) and extend displays with the keyboard shortcut (Command + F1). In Yosemite however, when I try to use this shortcut, my mac just makes that "thunk"/"beep" kind of warning sound like when you try to move a file to the trash if the file is still open and the display does not get mirrored.
I checked in system preferences > keyboard > shortcuts > display and there are only two shortcuts listed there:
There is no + button to add a keyboard shortcut because Apple says it will not allow you to create custom keyboard shortcuts for anything except "App Shortcuts" but this is not an app shortcut. It's a system shortcut. I have never modified any of the shortcuts for anything on this machine. Where did the shortcut for toggling mirror displays go? Why is it not displayed in the options on this panel? Did they remove it in Yosemite or is there something I need to do to get it back?
I've looked through the other panels (Services, Spotlight, etc.) but I don't see this shortcut or any other shortcuts for the keyboard listed under any of them. It seems to me like there should be a few more than just two keyboard shortcuts right? How can I get the "Toggle Mirror Display" shortcut?