Source : Free On-Line Dictionary of Computing

mouse ahead
     
        The {point-and-click} analog of "{type ahead}".  To manipulate
        a computer's pointing device (almost always a mouse in this
        usage, but not necessarily) and its selection or command
        buttons before a computer program is ready to accept such
        input, in anticipation of the program accepting the input.
        Handling this properly is rare, but it can help make a {WIMP
        environment} much more usable, assuming the users are familiar
        with the behaviour of the user interface.
     
        [{Jargon File}]
     
        (1994-12-05)