Rated 5 out of 5 stars

@Domènec: The latest version 1.2.3 doesn't appear to work on Local Folders (the "Flags" tab is not shown) - I don't know whether this is a bug or intentional (the later is more likely). The "Flags" tab appears in the "Folder Properties" dialog for IMAP folders, where the original problem this extension tries to solve resides.

This review is for a previous version of the add-on (1.2.3).