Naw, but if I had to guess, the background image is a GIF file...with alternating pixels that are more transparent than the next...that way it gives the 'see-thru' effect.
Donate to UBBDev today to help aid in Operational, Server and Script Maintenance, and Development costs.
Please also see our parent organization VNC Web Services if you're in the need of a new UBB.threads Install or Upgrade, Site/Server Migrations, or Security and Coding Services.