Editing text following a combining diacritical (and probably other combining characters) causes off-by-one style insertion/deletion errors in subsequent text.


To reproduce:

* Begin composing an message with either plain text or HTML formatting

* Paste the following (the 'á' below is an 'a' followed by b'\xcc\x81'):

á some text here

* Insert or delete text anywhere before the end of the following text.


In contrast, the same but with a single char representing 'á' doesn't have the same buggy behaviour:

á some text here