Better notice and UX when logged out user tries to post

[mbijon]

If you're logged out and try to 'Save Draft' from the Admin, then WordPress displays a small red notice box but you're later redirected to the login screen. The redirect causes you to lose the Draft post (there are browser plugins that help here, but they're not built-in to WordPress).

A better UX for logged out posting is in the P2 theme. It opens a popup saying you're logged out and disables the form posting capability. Can we attempt a similar, more-obvious UX for Admin?

This bug is detailed better here by Daniel Bachhuber:
​http://danielbachhuber.com/2012/05/01/notify-when-logged-out/

[SergeyBiryukov]

Related: #13942

[mbijon]

Thanks Sergey. I'm marking this a duplicate of #13942

Sorry about the duplication, searching for 'logged out' apparently doesn't show results for 'logged-out' very high up.