We've suspended development of Draftable for Gmail for the immediate future. This extension can be safely removed.
***This was a prototype that has been discontinued. It will not work for new users!***
Draftable automatically indexes your email, so it can show you when something you've just received is a new version of something you already have.
It knows when attachments are related, even if they're in different conversations, have different filenames, or are in different formats.