Typing /join #example does not add #example to the list of channels in the sidebar, or change the view to that channel. It also appears not to produce the expected server-side change (the official Slack client doesn't see the join).

Typing /part #example does seem to unsubscribe the user from that channel on the server side, but the UI in Ripcord is confusing (the channel disappears from the sidebar, the tab remains open and shows a message "This account cannot post in this channel.")

From discussion in IRC, it would be reasonable for /part #example to cause the current tab to switch to displaying the "next channel" from the sidebar.