(gdb) bt
#0  0xb75d163c in g_type_check_instance_cast () from /usr/lib/libgobject-2.0.so.0
#1  0x080b8630 in gossip_telepathy_chatrooms_join (chatrooms=0x8238dc0, room=0x82855c0, callback=0x807cc10 <group_chat_join_cb>, 
    user_data=0x0) at gossip-telepathy-chatrooms.c:152
#2  0x080b26a0 in telepathy_chatroom_join (provider=0x80d66a0, chatroom=0x82855c0, callback=0x807cc10 <group_chat_join_cb>, user_data=0x0)
    at gossip-telepathy.c:2036
#3  0x0809fedf in gossip_chatroom_provider_join (provider=0x80d66a0, chatroom=0x82855c0, callback=0x807cc10 <group_chat_join_cb>, 
    user_data=0x0) at gossip-chatroom-provider.c:174
#4  0x0807ce2d in group_chat_join (chat=0x81ec180) at gossip-group-chat.c:403
#5  0x0807d8f8 in gossip_group_chat_new (provider=0x80d66a0, chatroom=0x82855c0) at gossip-group-chat.c:1948
#6  0x0808744b in new_chatroom_dialog_response_cb (widget=0x82030b8, response=-5, dialog=0x8287b98) at gossip-new-chatroom-dialog.c:703