Prevent closing browser tab while saving

[PVince81]

1. Open text editor
2. Type in some text
3. Hit save
4. While saving, close the browser window

Expected: a popup appears (beforeunload style)
Actual: browser gets closed, sometimes file not saved

[phil-davis]

@PVince81 I do not see any "save" button - was there one in the past?
It seems to now just auto-save "all the time". If I make edits and do not like them, there is no chance to cancel - "the system" seems to have already saved my mistakes.

Somewhat related, I raised #205 - the close button can be pressed too quickly and recent edits are lost.

[PVince81]

@phil-davis the save button existed in ancient times and has been designed away, you might find it with a bit of git or github archeology.

cc @tomneedham

[phil-davis]

So this can be closed?
Because if there is no save button, then it can't be broken.