Add/remove workspace in kiosk mode

[mark.brandis at gmx.de]

Hi!

I use the kiosk mode of xfce for customer computers with the following configuration:

[xfce4-panel]
CustomizePanel=root

[xfce4-session]
CustomizeSplash=root
CustomizeChooser=root
CustomizeLogout=root
CustomizeCompatibility=root
Shutdown=root,USER1,USER2
CustomizeSecurity=NONE

But when I use the middle mouse button I can still add and remove workspaces. How can I disable that? I still need the middle mouse menu (running application menu).

Thanks in advance for any help
Mark