When dealing with the issue
XWIKI-4275 I figured out that I can't delete a page when there's an image attached to it; try the following:
create a new page
insert a (H1) header
insert an image
insert a second (H1) header
click BACK TO EDIT
click SAVE & VIEW
click the section editing icon next to the second (H1) header
==> the editor opens for the entire page content (this is issue
The new issue is: you can't simply delete the page created with the aforementioned procedure; if you try, you'll be redirected to the trash bin alright, but the page is still there; and even if you delete it from the trashbin it stays there. The reason for this is that there's the image attached to the page; when you delete that first, then you can delete the page afterwards.
Here's a screencast demonstrating the 2 issues above: http://screencastle.com/watch/664deb09034dcb3711651e865a7f0b62
Don't hesitate to make me do any tests or whatever I can do to get this fixed.