All vertices visited are connected in order they are visited. The little square on the top is blue when your last polygon does not intersect the Start-Goal line and is red when it does. It blinks from black to white when the planner is discovering the path. If it stops blinking, either your system has slowed down significantly, or stack allocation has been exhausted in some way. In the latter case, you may have to restart your browser.
Some bugs remain.
HAVE FUN and discover them.