Hello, I am using your app and it looks great! I have some suggestions for quality of life (and in some cases, security):

• OMEMO keys should be "Undecided" by default In some cases, people have many OMEMO signatures on their accounts. Which one is currently in use or on their devices is uncertain, and all should be unverified as a default. Trusting all and having to manually select all or some fingerprints as "Undecided" is bad practice. Trust should always be in total control of the user using the program - never decided for them.
• When OMEMO is switched on for the recipient, the UI should reflect that with a "last seen" indicator When a person with multiple signatures switches on OMEMO and sends a message using an OMEMO key, the UI should reflect transparently that the key was seen. All signatures should have a "last seen" indicator on the selection menu with a date, with the default being "Last seen: never". This prevents the need to figure out which key to use, since the on-going conversation can be a source of trust.

Those are some things that I have thought of. Thank you for making this app.