1) In gedit, create a new document, for example with 5 lines:

a
b
c
d
e

2) Save this document (for example "test.txt") and close it.

Actual result: the document size should be 9 bytes, but it's 10 bytes:

$ stat -c %s test.txt
10
$ cat test.txt 
a
b
c
d
e
$

See the newline displayed by `cat` after the character "e".

Expected result:

$ stat -c %s test.txt
9
$ cat test.txt 
a
b
c
d
e$

Note that I obtain the expected result when I do these steps with the editors Geany and Leafpad.