OS X supports a feature called Hot Corners, in which moving your mouse to a far corner of your screen invokes functions such as window management features of Mission Control, starting or disabling the screensaver, and activating Notification Center.
To set this feature up, go to the Desktop & Screen Saver system preferences and click the Hot Corners button. In the panel that drops down, you can select an action for each of the four corners of your screen.
While potentially useful, Hot Corners are easy to inadvertently activate. For instance, if you have the top-left corner configured, then you … Read more