Purpose With ColumnSize you can change the column width in a table control.
Examples ColumnSize [Material] 8

ColumnSize [Table.2,Material] 8

Format ColumnSize [column] n

ColumnSize [table,column] n

n is the new column width in the table display (number of characters).
The table name should be specified if there are 2 or more tables on the screen and the column name is not unique. You name the table by its title, if a table title is shown, or otherwise as Table, Table.2, ... If you click on View->Screen elements in GuiXT you see the correct name of the table.

ColumnSize [...] 0: If you specify width 0, then the column is not displayed.

If the table is already customized by normal SAP means, and you use GuiXT in addition, then the GuiXT script overrides.

& Tricks
ColumnWidth changes only the visual width of the column. ColumnSize changes the field size of the column fields both for data entry and display.
Components GuiXT