CamelMessageInfoBase level "dirty" flag somewhere?

Hi,

I am implementing camel_folder_sync().

It would be really nice to know, when loping over the message summaries,
if a summary has changed since it was loaded.

Imagine that the CAMEL_MESSAGE_FLAGGED flag has been set by the user in
"CamelMessageInfoBase.flags". Is there any way for my provider to detect
if that flag has been set by the user or must a poll the server-side
message to detect any changes?

Likewise for other flags. Changes to message flags since the last
summary load should be detectable by the provider for performance
reasons. A "message_info_dirty" somewhere would be nice.

Is there a way to achieve that?

Thanks,
  jules