[Rd] Line numbers above 99 not readable in editor (PR#9304)

[fuss-h at ulster.ac.uk]

Full_Name: Hendrik Fuß
Version: 2.4.0
OS: Mac OS 10.4.8
Submission from: (NULL) (201.27.210.144)


On Mac OS, in the file editor, line numbers on the left-hand side will be
truncated if greater than 99. They show up as e.g.:

12
12
12
12
12
12
12
12
12
12
13
13
13
13
...