Description of problem:

The attachment count as displayed above the attachment bar at the bottom of the
compose message window can have an incorrect attachment count when attachments
are removed from the attachment bar.

Version-Release number of selected component (if applicable):

2.8.3

How reproducible:
Every time

Steps to Reproduce:
1. Add an attachment to a new email message
2. Remove an attachment from the email message
3. Attachment count should be zero, but its still left at 1

Trying the same procedure with larger numbers of attachments leaves the count at
the max number of attachments, so it looks like the remove code fogets to
decrement the counter.



Expected results:

The count should reflect the number of attachments.