n and m are optional (m cannot be specified without n).
n represents the width of the list-box in characters and m the
The list of possible options is currently empty. This item is included
for future developments. If you include a help string in square brackets then
you must also include an empty options list.
num_items is the number of items in the list. If m is less than num_items
then a scroll bar is presented.
sel is an array whose elements are set to 1 if the item is selected
otherwise to zero.
items is an array of text entries, one for each item. Blank entries at
the end of the list are not displayed. This means that you can use blank
entries to create a list that can be changed dynamically.
%ms will take a pivot %pv - Pivot.