An achievable option in the short term would be to do the following:
1) Fix the DCS issue as I suggested.
2) Check if the terminal supports SIXEL (there is a code in DA or DA2, or perhaps we need a flag).
3) If the terminal supports SIXEL, pass it through, if it doesn't then ignore it.
This would allow SIXEL to display on output although it would be corrupted as soon as tmux redraws. It would be a start however and could be added to tmux immediately.
1) Fix the DCS issue as I suggested.
2) Check if the terminal supports SIXEL (there is a code in DA or DA2, or perhaps we need a flag).
3) If the terminal supports SIXEL, pass it through, if it doesn't then ignore it.
This would allow SIXEL to display on output although it would be corrupted as soon as tmux redraws. It would be a start however and could be added to tmux immediately.