Comment 2 for bug 417749

This is related to this bug in Ubuntu: "Changing workspaces via scrollwheel on desktop is problematic"
https://bugs.launchpad.net/openshot/+bug/400769

What happens, that if the scroll wheel on the mouse is used on an empty area on the desktop, the work space will switch. This is a feature of compiz, but so annoying, that this function will be removed.

It seems like the the preview pane is considered bij compiz as an empty area of the desktop, thus behaving like described in the Ubuntu bug. Maybe this can be sorted out why the preview area is functionally 'transparent', but the other option is to simple wait (Karmic) for the removal of the compiz function.