VERY-IMPORTANT: Fixed a severe issue where shapes ended up being shared
by several ShapeGraphicalRepresentation.

The following scenario allows to reproduce the problem:
1) Create new palette (in VPM)
2) Drop 2 rectangles
3) Change the background color of the first one
4) Change the shape of the second one (let's say to a diamond)
5) Select the first one again and change the shape, also to a diamond
6) The 2 shapes now have the same color
7) You can change the background of the first one as much as you like,
the second one will always follow and use the same background.
LOW / Removed log