This extra pane in Exposé does not appear if you have a Wacom tablet with a multi-button mouse (or puck as CAD vendors like to call it.) Guess Panther does not view it as a true rodent, though when booted from the Panther CD it functioned fine - slow, but fine.

However, using the temporary-reassign-FKey trick lets me put F9 - 11 on the mouse... err... puck's unused buttons.

Thanks for the suggestion!

There's another way to get the Wacom to behave. Assigning F9 to the middle button is the easy way, but you can assign the Exposé mouse functionality before you install the Wacom driver and it all works. If you've got the Wacom software installed, you could maybe uninstall it first, or borrow a friend's non-Wacom multibutton mouse, set up the functionality (quit System Preferences first), and then unplug.

Essentially, the Wacom software can deliver a true middle-click, but it doesn't let Apple know that it's a regular multibutton mouse.