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.

Version: unspecified
Severity: major