Please describe the problem:
When a Cc: header contains more than one address, they are separated by commas.
When you want to delete an address, you might place the cursor at the end of the
line and press 'backspace' until it's all gone.

However, when you've deleted all but the trailing comma, the previous address
becomes selected -- and the final press of backspace actually deletes the
_whole_ address, instead of just the comma.

Steps to reproduce:
1. Enter 'fred@example.com, jane@example.com' into a Cc: header
2. Press backspace 17 times, so that the header reads 'fred@example,com,'
3. Press backspace one more time. Instead of the comma disappearing, fred's
address becomes highlighted.



Actual results:


Expected results:


Does this happen every time?


Other information: