SMART datagrid v.1 > Classes > GridBase
In grid columns, it will only return ValueColumn as array. If parameter visibleOnly is true, it will return the ones being displayed currently, that is, only the columns of which visible is true.
ColumnGroup is not ValueColumn.
var col;
var columns = grid.getValueColumns();
for(var i = 0; i < columns.length; i++) {
col = columns[i];
col.setWidth(col.width() * 2);
}