VASL stack viewing

Howdy!

I just switched from Windows XP to Windows 7. When I play any VASSAL 3.1.14 version but VASL module and I try to view a stack’s content by putting the mouse on it, no problem. This doesn’t happen with VASL (5.9.1 version). Any idea? When I used to run XP I hadn’t such a problem.
Thanks in advance

Stefano