What is System Trust
seahorse currently has a System Trust, which is always empty, and a Default Trust, which is actually the real system trust. I know the separation is historical and predates the modern system trust by a long time, but I have no clue what this difference is for. Is it for certificates manually trusted with the 'trust' command? There is no graphical way to add or remove certificates from either, so I don't know how certificates would ever wind up under System Trust otherwise.
Since 99% of users will never have any modifications to the system trust, I suggest getting rid of the separation between System Trust and Default Trust. Or: show them only if nonempty, and rename to be less confusing.