[TYPO3-core] Alert before leaving unsaved changes

[Robert Wildling]

Hi, T3 team,

When having started editing some content, and leaving it, there is no 
warning about unsaved changes. I wonder if I miss something or if this 
is a missing feature?

If it is really not implemented, i would like to know if you plan to do 
build in such a feature. What do you think abot it? Would be great to 
read your opinions here.

Thanks, Robert