Application/document control close closes the active application window or document window
To close the application:
Click the button in the upper right corner of the title bar
Or click the application/document control icon in the upper left corner of the title bar and select Close,
Or right-click the title bar and then click Close,
Or press ALT+SPACEBAR+C (application) / ALT+HYPHEN+C (document),
Or press ALT+F4 (application) / CTRL+F4 (document).