1.) Connection lost Message:
"You have lost connection to the 4Minitz server.
You will lose unsaved data if you close your browser.
Click icon for reconnection attempt.
If problem persist, contact server admin."

• Check usability on smartphone!

2.) Use window.onbeforeunload()
See http://stackoverflow.com/a/1704783/2580805
message: "Do you really want to leave 4Minitz?"