Yay! This is cool.

I wrote something like this myself a while back: http://41j.com/hterm/

I recommend checking out libvterm (http://www.leonerd.org.uk/code/libvterm/). It abstracts out of lot of the v220/xterm terminal rendering code and is very neat. I'd love to see it get more support.

Also nice to see Sixel support (graphical terminal are fun!).