Subject: Centre of mass change of melting ice + tray sys. in gravity-free hall?

What will be the change in centre of mass of a system of ice block and tray 
when the ice melts in a gravity- free hall? The size of the tray is quite large 
as compared to the ice cube. Of course, since the mass of ice and subsequent 
water remains the same, the volume will contract on melting. But exactly how 
will the water cube act? Thank you.

Re: Centre of mass change of melting ice + tray sys. in gravity-free hall?