'internal method for determining above or below client.
Negative direction is to top'

def vertical_traversal(self, direction):

    (column, row) = (self.column, self.row)
    row = ((row + direction) % len(self.get_column(column)))
    self.clients.current_index = ((row * self.columns) + column)
    self.group.focus(self.clients.current_client)
