Typing at the end of an contenteditable element having a :first-letter style applied on it only replaces the last character in the element.
<div class="someclass" contenteditable="true">Some text</div>
Click at the end of the DIV and start typing.
Actual result: the last character from the DIV is replaced with the typed character.
Created attachment 31346 [details]
Testcase showing described behavior
Another linked misbehaviour:
Typing a space at the end of the very same editable region duplicates the text.
*** Bug 41514 has been marked as a duplicate of this bug. ***
the same bug occurs in Windows