I recently found that Nexuiz always tells me on startup that libOffscreenGecko.so is missing. So what it's supposed to do and do I need it?

You do not need this. It was used for this: http://blackhc.wordpress.com/2008/02/18/edu2p-stuff/
Read more about the project that used it at http://blackhc.wordpress.com/2008/03/18 ... ostmortem/

Thanks - insightful reply ...

Ok I have gotten this error as well. Even if it isn't used anymore Nexuiz still says it needs it sooooo, Why and how do we fix it?

It does not say it NEEDS it. It tries to load it, just like DP tries to load other optional libraries (e.g. libpng, about no map uses it).

If it's missing, that feature simply won't work - but as Nexuiz does not uses it, it does not matter.