If an AT attempts to access a defunct accessible object, the QT host app may crash

Preparation:
1. Do these things: http://userbase.kde.org/Accessibility/Getting_Started
2. Configure KMail with a folder with at least three messages in it

Steps to reproduce:
1. Launch the attached event listener (kmail-crash.py)
2. Launch KMail
3. Click on the folder prepared in prep step 2 above
4. Click on the third (or later) message down
5. Press Left, Left, Ctrl+Left in fairly rapid succession
6. Wait

For me, KMail reliably segfaults. (See attached backtrace.) The corresponding terminal output looks like:

object:state-changed:focused [table cell | Local Folders]
focus: [table cell | Local Folders]
object:state-changed:focused [table cell | Local Folders]
object:state-changed:focused [table cell | gnome]
focus: [table cell | gnome]
object:state-changed:focused [table cell | gnome]
object:state-changed:focused [table cell | orca <bugzilla@gnome.org>]
focus: [table cell | orca <bugzilla@gnome.org>]
object:state-changed:focused [table cell | orca <bugzilla@gnome.org>]
object:state-changed:focused [table cell | ]
focus: [DEAD]
object:state-changed:focused [DEAD]

Notes:
The test case is admittedly a tad artificial, but it was created to isolate a reliable crasher seen when using Orca to access KMail. Orca processes events asynchronously, and specifically checks to see if an object has STATE_DEFUNCT before poking at an object too hard. But as you'll see in the event listener, the mere act of printing e.source seems sufficient to crash KMail. (When I just print e.type out without e.source, the crash doesn't occur.)