event OnRowCreate

    protected void GridSelCourses_RowCreated(object sender, GridViewRowEventArgs e)
    {
        Unit aaa = new Unit(9, UnitType.Percentage);
        e.Row.Cells[0].Width = aaa;
        aaa = new Unit(4.5, UnitType.Percentage);
        e.Row.Cells[1].Width = aaa;
        // and so on
    }