GUADEC: A message from the release team

Actually, that is a mess to promote such lovely hacks as the Windows 7 auto-hiding icons as the "blessed" solution. Running programs in programs with the process model that panel applets have will not really be supported since that particular breed of COM-like objects are being discontinued.

Keeping the shim would mean that you would need to retain the whole thing indefinitely.

The good part however, is that your beloved and much needed classical panel will still be there, and will be what you have unless you have shiney 3D-like accelerated graphics on your computer. It will be maintained and supported.