Description of problem:
After composing message in sylpheed and pressing "send", the message is sent and
sylpheed segfaults when it attempts to close the compose window when there is
highlighted text in the message body.

Version-Release number of selected component (if applicable):
gtk2-2.9.1-1
glib2-2.11.1-1

How reproducible:
Always

Steps to Reproduce:
1. Start sylpheed and compose a message (or "sylpheed --compose")
2. Set To: and Subject:
3. Highlight some text in the message body.
4. Click "send".
  
Actual results:
Sylpheed segfaults.

Expected results:
Sylpheed continues to run.

Additional info:
I start this report with gtk2-2.9.0-4 and glib2-2.11.0-1 but while downloading
the debuginfo files I ended up with the new version.  The problem still exists
and the attached backtrace is for the new version.

An initial guess is because of the highlight text, there is some sort of
dangling reference.