I was trying to zoom to fit the entire project, so I selected everything with Ctrl+A, then wanted to zoom to fit using Alt+S, but I accidentally pressed “Alt+A”. According to the Key Commands, this “Activate/Deactivate Focused Object”. What exactly did I do? There is nothing int the Undo History, so maybe this was benign.
Thank you!
P.S. Windows 7, Cubase Pro
I think you are fine. I assigned a key to the command and played around with it and couldn’t figure out what it did. But since it is an edit command, if it actually did something in your Project it would show in the Edit History. Since it didn’t you’re cool.
For future reference when something happens where you are not sure if you changed stuff or not; then File/Revert is your friend. This assumes you save frequently - but we’re all doing that right 
Coincidentally I have Alt+A assigned to a Macro that does exactly what you were going for, select everything then set Locators.
Thanks, Rodger. Yes, I went back to a previous version just to be safe. There doesn’t seem to be anything about this command in the manual either! Just a mention of “Activate/Deactivate Focused Object”. I don’t want to accidentally deactivate something, so I’m going to remove or reassign this command. Too easy to blunder into something without realizing it.
The Key Commands are woefully under-documented. There are a bunch where it is hard-to-impossible to figure out what they do; even for very experienced users.
I realize this is old, but I too have not been able to work this one out, please Steinberg, what does this do?
The best I found is the below, didn’t quite get it but it might help someone else
Activate or Deactivate Focused Object (Alt + A): For activating or deactivating focused object of editing process we can press Alt + A key of keyboard that means first time when we press these keys it will make this command active and when we again press these keys it will deactivate this command.
It’s from here
Since this thread was last active @ggmanestraki has documented all the Key Commands 
And according to it
Activate/Deactivate Focused ObjectDefault: Alt A
Function: Multifunctional key. Activates/Deactivates whatever can be activated/deactivated when it’s focused.
Keyworthiness: 10
Note: Works on headers (Inserts, Sends, EQ, Strip) to bypass them. Works on specific controls that have focus, e.g. an equalizer band. I suspect there are a million other places where this works, but getting keyboard focus to test it out is tough.
Too bad we don’t have more (and better) Key Commands to set the focus.
Agreed. There are many commands in Cubase that can function on several areas (Track/Channel Visibility Configurations, I’m looking at you!) which makes more complex macros or PLEs require 3rd party tools to ensure the command is sent to the right window.
Exactly.