if you choose in the settings->controls "middle click opens Windows Start
a middle click in the free space of the taskbar also opens the windows start
in Vista and win8 not.
if you choose the classic start menu ---- no sideeffect
This side-effect is a bug. It's happening on only Windows 7 when Classic
Shell's Start Button is NOT enabled and middle click is set to open Windows
Start Menu. It will be fixed in next version.
This is fixed in version 3.6.2