SuSE 10.0 Gnome panels on big desktops

I've got SuSE 10.0 running nicely on an AMD-64 box with an ATI X800GTO graphics card. I'm using the ATI provided drivers to run "One Big Desktop" across two 1280x1024 monitors. I run a similar set up on an older SuSE 9.2 box as well. On the 9.2 box the top and bottom panels expand across the whole desktop (2560 pixels wide) but on the 10.0 box they will only expand to cover one monitor (1280 pixels wide). I've looked in the configuration database but I can't see anything abot this. Is there an easy way to make them expand to full desktop width ? I know I could run a separate panels on each monitor but that seems like a messy solution to me. Peter