When ResizableColumns="True" and the mouse hovers over the header, an icon appears at the right side of the header. This icon can be dragged left or right to adjust the column width.
The updated column widths are remembered for the table for the current session.
ResizableColumns may not be used with header rows with columns spanning multiple columns.
With ResizeableColumns, when a column's Width attribute is set, it must represent pixels.
The default value is False.