This may be just what you’ve been waiting for: MKVToolNix 1.4.0.

To quote Mosu:

I’m releasing the new mkvtoolnix version including all the fancy new stuff. It’s v1.4.0.

So what has changed? Tons of new features, tons of bug fixes, tons of
new bugs ;) The more important things are: – support for MPEG-1 and MPEG-2 video read from PS and ES streams, – support for AVC (aka h.264) video from MP4 files, – support for concatenating files, – support for the new elements needed for menus, – support for WAVPACK4 lossless and lossy audio, – support for extracting VobSubs…

Finally, we’ve got VobSub support, menus, file merging, and new audio streams.

You can find it at the same place, same time.