Update the column and row numbering in the headers.

def reset_headers(self):
        """
        Update the column and row numbering in the headers.
        """
        rows = self.rowCount()
        cols = self.columnCount()

        for r in range(rows):
            self.setVerticalHeaderItem(r, QTableWidgetItem(str(r)))
        for c in range(cols):
            self.setHorizontalHeaderItem(c, QTableWidgetItem(str(c)))
            self.setColumnWidth(c, 40)