STACKKEYS <keystring>
        <keystring> =
            .r    : Ctrl-key (Letter).
            @Key     : Alt-key (@Number or @Letter).
            Char     : Literal character.
            "String" : String, enclosed in double quotes.
            'String' : String, enclosed in single quotes.
            Number   : Keyboard scan code (decimal).
            !        : Clear keyboard buffer.
            Whitespace (space and tab) is ignored.

        With this, you can "stack" keys in the keyboard buffer. The
        STACKKEYS can be overridden by commandline keystacking, which
        uses the same syntax.

        >>> See the Macros and Keystacking section for more info.