I need a way in C# to monitor system-wide keys such as Ctrl+A, so I can act upon that.
How could I get such an event, even when the keys were pressed with my App no longer in focus?
Joey
You can use the RegisterHotKey function to react system-wide to hotkeys. However, I wouldn't advise you to use something like Ctrl + A which has a meaning in many applications.
I don't think there's a managed way to do that. At an API level you can register system-wide hooks or global hotkeys.
Writing a keylogger? :-)
来源：https://stackoverflow.com/questions/985989/how-to-monitor-for-keystrokes-pressed-when-outside-the-app