ctrl key make a window disappear

[sammy hwang]

I have used mission control and a couple of customized short cut key on Yosemite Mac.
The thing is as soon as I press ctrl key, a window disappear to the edge. And I toggle it, pressing one more time,
the window get back to the center. I don't know why it happens.

I checked the system preference -> keyboard -> shortcuts -> restore default. It still dose the same.
I plugin the wireless pc keyboard and press the ctrl key. It still does the same thing.
Could you let me know why and what I need to do ?

 

[Spawn_Dooley]

F11 (fn F11 on a laptop) is used to "Show Desktop". Somehow you have set the Ctrl key to do this.

Have a look in System Prefs ~> Mission Control to check if your Ctrl key is set to "Show Desktop"

 

[sammy hwang]

Thank you so much, Spawn_Dooley!