Keeping the Unity Taskbar in only one Mac OSX Desktop

I use multiple desktops in Mac OS X (10.8)

On one of these desktops I run VMware Fusion (4.1.3). I tie it to the one desktop by right-clicking on the VMware Fusion icon choosing 'Options' and 'Assign to: This Desktop".

For the most part Fusion honours this setting, however when I run the (Windows 7) taskbar* it appears on every Mac desktop. Any clues on how to stop this?

* To get the taskbar I click on the Fusion icon in the top right and for the running virtual machine choose View -> 'Show Taskbar in Unity'

Thanks, Liam.