Wikimedia Bugzilla is closed!

Document:

 h2> Foo
 p> Lorem ipsum.
 h2> Bar
 p> Bla bla bla.

Steps:

* Put cursor in the first heading between "F" and "oo".
* Change text style to paragraph (via menu or or use ctrl-0).
* Observe cursor going wild (disappears in Firefox, appears outside the document in the margin in Chrome, bug 50442)
* Type 3 characters ("a", "b", "c")

Firefox result:

3 new paragraph appear.

 p> o [new]
 p> o [new]
 p> a [new]
 p> Foo
 p> Lorem ipsum.

And more on every subsequent keystroke. It seems to have copied this "o" from "Foo" somehow. And "b" and "c" never appear.