I was wondering why things were different on the two platforms.

By looking at the VM source code, I found that:

* � �3) The modifier keys are mapped as follows:

* � � � �Mac � �| �Win32

* � � � --------------------

* � � � Shift � -> Shift

* � � � Ctrl � �-> Ctrl

* � � � Command -> Left ALT

* � � � Option �-> Right ALT

Things are now clearer!