Room invite UX is confusing (usability issue)

[dkasak]

The current UX for inviting a user to a room is confusing due to having two separate screens:

• The main one, started by touching the circled + icon, to the right of the N/M active members element. This screen contains a text input area on the top saying User ID, Name or email.
• The secondary Invite by ID screen, accessible from the main one.

It is not clear why both of these mention the "User ID" and in what way they differ: when should a user use one and when the other?

The scenario in which this came up is the following:

• There are two rooms, P and Q.
• There are two users, A and B, both registered on this HS.
• User A is in both P and Q, but user B is only in Q.
• User A wanted to invite B to P.

User A then complained to me that entering B's user ID in the text input area on the main invite screen didn't allow him to invite user B to the room nor did it acknowledge his existence in any way. He did not notice the Invite by ID clickable element.

What is the reasoning behind the separation of these two screens? Could they be merged?

If it's relevant, this is on a home server we are running, not matrix.org. The client in question is Riot Android version 0.8.1.