The conversation tabs in Skype 4 for Linux may be not what you want. For example, if you communicate to different people in different languages, you'll have to annoyingly change the layout while your DE supports different layouts for different windows (this is how I use it and I find this layout switching policy really convenient). In this case you'd prefer Skype to start a conversation with a new person in a separate window (like it was in the old Skype 2 version).
To ungroup conversation tabs in Skype 4 on Linux and switch back to the separate window per conversation style:
- click "Options" in Skype 4
- go to "Chat" settings
- uncheck "Use default view".
That's it. Now you'll have the old good style of different chat in separate windows.
By the way, the icon in the top right corner of the conversation window toggles showing the contacts that are currently in chat.