hi,
you can do it easy.
i havn't C2 installed in this Pc, but i try to help.
just fix the volume min and max.
1. Put the SQUARE in min area and record its X position, assign its volume to zero "0"
2. put the SQUARE in max area and record its X position, assign its volume to max volume (goto help to know it)
3. Add drag drop behavior to the SQUARE and in on drop: compare the current X position and set it's value to volume.
try and tell me the result.