-Q2.D.5- scroll two listboxes with one scrollbar?

From: -II-  Tk Questions and Answers - How can I:

A2.D.5. Scrollbars have a '-command' option which is used to tell
scrollable widgets (e.g. listbox, text, entry) how to position
themselves when the scrollbar is moved.  This command typically
looks like:
    scrollbar .scroll -command {.scrollable_widget yview}
or
    scrollbar .scroll -command {.scrollable_widget xview}

Before the command is executed, however, it will have a space and
a number appended to it.  The number is a logical position index
which indicates how the scrollable widget should position itself.
Thus, to have a single scrollbar control two (or more) widgets,
simply use a procedure as the scroll command, and have that
procedure scroll as many widgets as you would like.  The procedure
should take a single argument (i.e. the logical position index).
For example:

    proc ScrollCommand {index} {
        .lb1 yview $index
        .lb2 yview $index
        .lb3 yview $index
    }

    scrollbar .scroll -command ScrollCommand

    listbox .lb1 -geometry 4x5 -yscrollcommand {.scroll set}
    listbox .lb2 -geometry 4x5 -yscrollcommand {.scroll set}
    listbox .lb3 -geometry 4x5 -yscrollcommand {.scroll set}
    pack .scroll .lb1 .lb2 .lb3 -side left -fill y

    .lb1 insert 0 a b c d e f g h i j
    .lb2 insert 0 0 1 2 3 4 5 6 7 8 9
    .lb3 insert 0 A B C D E F G H I J

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