Inconsistent handling of multi-line comments in the descript.ion file

[zezzagio]

The latest version of XnView MP (1.12.2 [10234] 64-bit (Oct 12, 2026) - Libformat 7.310 (Linux)) behaves inconsistently when processing multi-line comments in descript.ion files.

I am aware that there is no actual standard for this format. However, the convention used by previous versions of XnView MP was to:

• replace newline characters with the literal string \n;
• append a marker at the end of the comment to indicate that it is a multi-line comment;
• use the character pair "\x04\xC2" as this marker (a convention also used by Total Commander).

In the latest version, comments written according to this convention are still interpreted correctly when read. However, when writing comments, the final character pair becomes "\x04\xFFFD" (\x04 followed by the Unicode Replacement Character, U+FFFD).

As a result, when such a comment is subsequently read back, the \n sequences are no longer converted into actual newline characters and are instead interpreted literally.