[command + tab] Use it to Access your Mac when Something is Not Responding
Accessing your Mac when Something is Not Responding
When you are using an application, and it begins not responding, hold down command and keep tapping tab until you get to Finder (the smileyface).
Once in Finder you will be able to access your Mac, as need be.
Screenshot of Finder Selected: (Pasted onto a green background for Hi-Contrast)