'Generates lines across all columns
(each cell may contain multiple lines)
This will also balance the table.'

def _generate_lines(self):

    self._balance()
    for iy in range(self.nrows):
        cell_row = [col[iy] for col in self.worktable]
        cell_data = [cell.get() for cell in cell_row]
        cell_height = min((len(lines) for lines in cell_data))
        for iline in range(cell_height):
            (yield ANSIString('').join(_to_ansi((celldata[iline] for celldata in cell_data))))
