Implementing proper updating is simple in that sending stuff to PyDS is simple. However, having the GUI do the right thing is tricky:
When you modify an entry and switch to another, you have to offer a chance to save or discard.
If the user discards, you have to go back to the original data, so it must be saved somewhere else. And remember this:
Yeah, obvious python semantics. Lost an hour, though ;-)
What you want to do instead is:
If he saves, you have to upload.
Also, when he modifies, you have to update the post list realtime, so you see a coherent entity.
Not too hard, but it forces you to despaghettize code somewhat.