Ask HN: Group Chat client that works behind a proxy

I'd love to be able to use the Hipchat desktop client with my team, but our corporate network requires a proxy server to access the Internet.

Is there an app that meets these requirements:

  - Linux Desktop Client
  - Proxy support
  - Persistent Rooms
  - Image and file sharing
  - Desktop notifications
  - Firewall friendly (optional)
  - Commercial apps not a problem
  - No browser-only solutions!

I've tried a few of the Campfire desktop clients on Linux (such as Snakefire), but some messages seem to go missing or don't show up until the client has been restarted.

I've also come across another product called OneTeam (http://oneteam.im/), but there is almost no mention of it outside of their own website. So I'm a bit sceptical...