Window frame specification in SQLiteStudio

Question

I am running below code from the SQLite documentation on SQLiteStudio 3.3.3 :

SELECT a, b, group_concat(b, '.') OVER (
  ORDER BY a ROWS BETWEEN 1 PRECEDING AND 1 FOLLOWING
) AS group_concat FROM t1;

Where t1 is defined as :

CREATE TABLE t1(a INTEGER PRIMARY KEY, b, c);
INSERT INTO t1 VALUES   (1, 'A', 'one'  ),
                        (2, 'B', 'two'  ),
                        (3, 'C', 'three'),
                        (4, 'D', 'one'  ),
                        (5, 'E', 'two'  ),
                        (6, 'F', 'three'),
                        (7, 'G', 'one'  );

Instead of getting the expected result as shown in the SQLite documentation I get :

a	b	group_concat
1	A	B
2	B	C
3	C	D
4	D	E
5	E	F
6	F	G
7	G

How is this possible? Does this happen because I am using SQLiteStudio instead of SQLite? If this is the case, what are the rules for the frame definition of window functions in SQLiteStudio?