Sets the table column count.

        Args:
            count (int): column of rows

def set_column_count(self, count):
        """Sets the table column count.

        Args:
            count (int): column of rows
        """
        current_row_count = self.row_count()
        current_column_count = self.column_count()
        if count > current_column_count:
            cl = TableEditableItem if self._editable else TableItem
            for r_key in self.children.keys():
                row = self.children[r_key]
                for i in range(current_column_count, count):
                    row.append(cl(), str(i))
                    if self._editable:
                        row.children[str(i)].onchange.connect(
                            self.on_item_changed, int(r_key), int(i))
            self._update_first_row()
        elif count < current_column_count:
            for row in self.children.values():
                for i in range(count, current_column_count):
                    row.remove_child(row.children[str(i)])
        self._column_count = count