Steps to reproduce:
1. Launch Evolution and GOK.
2. Creat a new meeting, invite yourself to be an attendee.
3. Send the meeting invitation.
4. Receive the meeting invitation.
5. Select this invitation, press UI Grab in GOK.
6. Select HTML Container->go forward, or select HTML Container->go down.

Expected result:
Meeting invitation should be opened or hiden after these actions.

Actual result:
Evolution crashes.


How often does this happen? 
always

Additional Information:
The meeting is actually rendered by gtkhtml widget. When the go down button
pressed, the html is refreshed. But we don't handle the signal at this
time. So GOK ref to some outdated atk object. So manipulate these objects
will cause crash.


I will give out a patch soon.