Maximum percentage width for the current column.
If your list is 200 pixel wide and you set this
to 25, your column will not be wider as 50 pixel.
The special value -1 for this parameter means that
the maximum width is as wide as the widest entry in
Defaults to -1.
Starting with MUI Royale 1.1 this attribute has an applicability
of ISG. In MUI Royale 1.0 the applicability of this attribute was