Quaternion is a Matrix client written in Qt. It is capable of showing chat-rooms but it is not at all usable as a general-purpose chat client; it is way too buggy.
We tested version 0.0.9.4e.
Features And Usability
Quaternion will show you a window with chat rooms, if you have joined any, on the left side, a chat room in the middle and the chat rooms user-list on the right side. It is pretty strait forward.
Joining rooms is a matter of either selectingor in the menu. There is no local or global room list to choose from. You will have to enter a full Matrix room ID to join a room. The client does allow you to create a new room.
Quaternion will ask you for a Matrix server user-name and password every time you start it. It is capable of saving user-name and server but it can't save server passwords.
Quaternion will show an error message saying "Quaternion couldn't delete the access token from the keychain" every time you quit the program - if it doesn't just crash before you decide to quit it.
Quaternion can show images, but not videos, in chat rooms. Video files are shown using buttons allowing you to either open them or save them.
Verdict And Conclusion
Quaternion has the potential to become a great Matrix client. It is not as of version 0.0.9.4e released in April 2020. Quaternion is buggy, incapable of saving server passwords and it shows an error message when you quit the program. It is overall a bad experience.