ADpl_drives( [nTop], [nLeft], [nMode], [bProcess], [bConfig],;
        [cHelpId] ) --> <xSelection>
        ---------------------------------------------------------------
        Implements an ADvermenu-derived drives picklist.

        [nTop] and [nLeft] are the top/left coordinates of the picklist
        box.  Just like ADvermenu(), they default to 0,0.

        [nMode] is a numeric code that specifies the display format.
        The valid values are #defined in Frankie.ch

        #define DRIVE_LETTER_ONLY       2    // drive letters
        #define DRIVE_LETTER_COLON      3    // drive letters + ":"
        #define DRIVE_LETTER_PATH       4    // drive letters + path

        The default value is DRIVE_LETTER_COLON

        [bProcess] is a codeblock that gets EVALuated when a drive is
        selected.  It is automatically passed the currently highlighted
        drive (character string).

        [bConfig] has the same meaning as the [bConfig] in ADvermenu().

        <xSelection> is the return value.  It is either the selected
        drive or an array of tagged drives, depending on whether, the
        picklist is configured as a taglist or not.

        NOTE:  Unlike ADvermenu(), ADpl_drives() may not be configured
        to return the numeric index position of the selection.  It
        always return the selection itself (a character string).