question about tny_camel_folder_add_msg_async_default

[<Dirk-Jan Binnema nokia com>]

Hi,

Did some more valgrinding; I found the following, when saving
messages to draft. It seems this issue happens for all of the async
funtions in tny_camel_folder.

1) we're calling tny_folder_add_msg_async; the last parameter (callback
   data) is a struct of type SaveToDraftsAddMsgInfo
    (for example in modest_mail_operation_save_to_drafts_cb)

2) in tny_camel_folder_add_msg_async_default we create a new structure
   'info' of type 'AddMsgFolderInfo', and 
                   info->user_data = user_data      <=  this is our
SaveToDraftsAddMsgInfo

3) we're adding this info to the queue, 
   _tny_camel_queue_launch_wflags, and this 'user_data' is there called
'data'

 Here we create yet another structure 'item' of type QueueItem, and
                    info->data = data               <=   this is our
AddMsgFolderInfo

4) finally, we call the callback in 'perform_callback', which uses the
QueueItem:
	if (item->callback)
              retval = item->callback (item->data)
     
 so, we're calling our callback function with a AddMsgFolderInfo
structure, but
 the callback is expecting to get its SaveToDraftsAddMsgInfo. It will
also do a 
 g_slice_free etc., so it's easy to see how this could lead to crashes.

Not sure what is the best way to fix this; one rel. easy way would be to
add the 
user_data as a separate pointer. But, note that the queue api is also
used
from tny-camel-(store-)account and tny-camel-bs-mime-part, and there it
seems
the problem doesn't occur (because the functions there add there
user_data
directly to the queue, instead of going through the tny_folder_ ..
functions.

Best wishes,
Dirk.