private boolean clearSortInternal() {
		int count = getColumnCount();
		boolean notify = false;

		for (int i = 0; i < count; i++) {
			Column column = getColumnAtIndex(i);

			if (column.getSortSequence() != -1) {
				column.setSortCriteria(-1, column.isSortAscending());
				notify = true;
			}
		}
		return notify;
	}