The tab bar at the bottom of the chat area holds the things that can occupy the conversation region: Status, the one conversation you are reading, and — when that conversation has one — its Space. It is a switch between those, not a list of everything you have open.
Switching Conversations
Use the conversations sidebar on the left to move between channels and private messages. Click a conversation there and it takes the screen, replacing whichever one the tab bar was showing. From the keyboard, Ctrl+Shift+] and Ctrl+Shift+[ walk through your joined channels and open private messages without touching the mouse.
Switching Away vs Leaving
Reading something else does not leave the channel. A conversation you switch away from keeps receiving messages, keeps counting unread, and keeps flashing and playing its sound in the sidebar — you simply are not looking at it. To actually leave, use the × on the tab, or right-click the channel in the sidebar and choose Leave Channel.
Space
Space is a second view of the conversation you are already in, not a place of its own: the map replaces the messages and the message box keeps working. Switching to another conversation always lands you on its chat, so you never arrive in a map you did not ask for.
Buttons Beside the Tabs
The controls next to the tabs open something beside the conversation rather than replacing it: channel settings, user lookup, the conference and the P2P session. Each carries its label, so you can read what it does. On a phone the first two also slide the conversations and user list open over the chat. Find is not one of them — it lives in Edit > Find, in the Start menu, and on Ctrl+Shift+F.
