[nu5500]

The client that I am using (which you can download from https://products.office.com/en-us/skype-for-business/downloa...) keeps all conversations in one window with people listed down the left. I've never seen it starting new windows.

[douche]

This is an option in the client settings - "Enable Tabbed Conversations". I'm pretty sure it defaults to being turned on, because I always have to go in after an update and disable it to get my conversations popping open in separate windows again.

[knz]

> This is an option in the client settings - "Enable Tabbed Conversations"

Which client? The OSX client appears to have very limited configuration options.

[mda590]

The OSX client is quite awful. But, under Preferences > General, there is a "Show conversations in separate windows" option.