When last we met, I was having a few issues with QGraphicsView, which I eventually pinned down to Emscripten's occasional mishandling of combinations of doubles and 64-bit ints. I submitted a bug report, and received a lightning-fast fix, so now QGraphicsView seems to be working perfectly :)
Here are a handful of demos: make sure you have plenty of RAM free if you are using anything other than a recent Chrome :)
(Note that, sadly, Konqueror/ Rekonq won't work with emscripten-qt, presumably due to lack of typed array support(?))
The next things to work on are a small helper library for making asynchronous dialogs slightly more convenient to use, and less-sketchy keyboard support (you'll notice that you can't currently type any punctuation, and selecting text with the keyboard is not quite right). After that, I'll upload more of the Emscripten-ised Qt examples and then get back to working on Kate's Vi mode :)I've added a bunch more documentation (plus a few more screenshots!) here.