A whole bunch of buttons can be disabled, a look through the preferences will show you the following:
The last one will make sure no promotional buttons are shown anywhere, not in contact list and not in chat window.
To be complete, in the conversation window there is also a button called Online and Local Logging. This button shows you if chat logging is turned on or off for that conversation. Local means saving chat logs on your HDD, Online means saving chatlogs online in your MyPlus! account (
msgplus.net)
You can also choose whether you want the button to show and if shown if it should animate or not by clicking on it.
You can reactivate it from the Plus menu in the conversation window
If you don't see the menu in the conversation window go to the bottom right (Windows Live Messenger 2011) to enable it