Doesn't protect from closing administrative overlay

If user is using the administrative overlay for edits, then they don't have protection from closing the overlay or from clicking on another tab in the overlay.

Steps:
1) Enable overlay
2) Edit existing page
3) Start typing changes and navigating to other fields
4) Click the X to close the overlay. OR Click View Draft.

Actual result: Overlay closes.
Expected result: Get the dialog warning that you will lose your work.

Only workaround is to not use overlay for editing pages.