MKVToolNix 60.0.0 (64-bit)

What's new in this version:

New features and enhancements:
- all: IETF BCP 47/RFC 5646 language tags: added support for language families from ISO 639-5 that aren't part of 639-2
- all: IETF BCP 47/RFC 5646 language tags: implemented support for Alpha 2 country codes of the "user-defined" category: `AA`, `QM`–`QZ`, `XA`–`XZ` and `ZZ`
- all: IETF BCP 47/RFC 5646 language tags: updated the various lists of valid subtags from the official specs
- MKVToolNix GUI: multiplexer: pressing the keyboard shortcut for the track's anguage" label (Alt+L for English) will now open the language dialog
- MKVToolNix GUI: multiplexer: added an option in the preferences for turning off the colored boxes indicating which file each track belongs to

Fixed:
- all: IETF BCP 47/RFC 5646 language tags: fixed validating extended language & variant subtags against their allowed prefixes (e.g. a valid tag with a country code as in `de-CH-1996` is recognized as valid while two generally known variants that aren't allowed together as in `de-1901-1996` is recognized as invalid).
- all: IETF BCP 47/RFC 5646 language tags: when looking up a language for a two- or three-letter code, the programs will no longer compare that code with language names as that was unintended, ambiguous (e.g. the code "Ga" could be interpreted as the 639-2 alpha-2 code for "Irish" or as the name of the language called "Ga") and only worked with languages whose name was at most three letters long.
- mkvmerge: HEVC/H.265: appending Matroska files with HEVC tracks might lead to the loss of the first couple of frames from each of the second and all following files
- mkvmerge, mkvextract: HEVC/H.265 parser: fixed the programs aborting when parsing VPS or SPS NALUs with invalid content due to unhandled exceptions
- MKVToolNix GUI: multiplexer: when the option "use legacy MIME types for font attachments" is enabled, the GUI will now use `application/x-truetype-font` for font collection files.
- MKVToolNix GUI: multiplexer: fixed escaping the `mkvmerge` argument in the "Show command-line options" dialog for the "Windows (cmd.exe)" mode
- MKVToolNix GUI: multiplexer: when adding multiple files at once, the GUI will sort file names with numbers the way a human would expect it to. For example, `1.mp4`, `9.aac`, `10.srt`, `11.srt` are now sorted exactly that order instead of `1.mp4`, `10.srt`, `11.srt`, `9.aac`.
- MKVToolNix GUI: header editor: the header editor will now honor the "use legacy MIME types when adding font attachments" setting when adding new attachments