Display unshared size

[jondo]

In the snapshots list, I would like to see a column displaying the 'unshared' size, i.e. the amount of snapshot data that is not shared with any other shapshot. Is this feasible? In case computing this takes too long, it could also only be available after manually triggering the computation via menu item.

I know this 'Unshared' column from Timeshift's btrfs filesystem snapshots:

I am currently using Back In Time 1.2.1.