public void shiftMode() {
		finalEdit = true;
		LRParseTable table = getParseTable();
		// Determine which rows and columns have ambiguity.
		cellEditors = new TableCellEditor[table.getRowCount()][table
				.getColumnCount()];
		for (int r = 0; r < table.getRowCount(); r++)
			for (int c = 1; c < table.getColumnCount(); c++) {
				cellEditors[r][c] = null;
				SortedSet set = table.getSetAt(r, c);
				if (set.size() <= 1)
					continue;
				table.setValueAt(set.first(), r, c);
				cellEditors[r][c] = new DefaultCellEditor(new JComboBox(set
						.toArray()));
			}
	}