Message History Visibility settings are misleading

[ancatut]

This issue kinda ties into #1561.

Basically, with how the permissions under Message History Visibility are currently worded, an E2EE room admin expects to be able to give joiners the ability to see the message history from prior to joining by selecting "All Messages."

In practice, when a new member joins, history messages in that room are shown to them as "unable to decrypt."

I believe this section of the settings should not claim to enable "Message History Visibility - All Messages" as long as this feature is not actually implemented.

[u9000-Nine]

So the feature is implemented (as in you can see the messages), but you can't decrypt them because they weren't sent with a key for you. You can tell that there's a difference because if you disable it new users will see room with no messages at all.

Might be worth making some text appear clarifying that new users will not be able to decrypt old messages, though.

[ancatut]

I understand the distinction now, but only after reading through these comments here :) Agreed that it would help to add clarifying text about how new users would see that messages had been previously sent in the room, but not able to decrypt them.