What's even more cool is the 'Share flow' link in the sidebar that will give you some html you can copy and paste to embed the flow viewer in another site... including in this forum...
There's more work to do to improve the overall experience. For example, it doesn't know about the icons/colours of contrib nodes so they all get a very generic appearance - but this is a great starting point.
And noticed the subflows weren't connected. I began zooming around and switching between tabs and somewhere along the lines, I was zoomed out and couldn't zoom in again:
I think d3 isn't capable of doing framing content into the viewable area (or at least I didn't find it), what I did therefore was to readjust the size of the svg to be the same size as the containing div and then setting the viewBox of the svg to the bounding box of the content:
that seems to be a flow where someone has included the flow.json into the description field when creating the flow - instead of writing a description of the flow