first of all: Thanks for the improved audio multitrack support!
Only a minor issue:
When opening an mkv movie the Audio-selector always shows (MP2,Stereo,128kbps) for mp3 tracks - no matter what the tracks really are.
Seems to be a display-only issue, saved in copy-mode they keep their orignial bitrates and modes.
probably a .ts file that starts at 128 then changes to 256.
The tracks came originally from an ts stream, copied to the mkv by ffmpeg (-c:a copy)
It's just a bit strange that all other tools show (ffmpeg, mkvinfo, xine...) them as 160/192/256kbps, only avidemux says 128kbps.