BUG: update the color-bar at each draw NEEDED for macular
once a chain as been defined:
dtkVisualizationDecoratorClutEditor *decorator_clut_editor_mesh = new dtkVisualizationDecoratorClutEditor;
dtkVisualizationDecoratorScalarColorMap *decorator_scalar_color_map_mesh = new dtkVisualizationDecoratorScalarColorMap;
(*decorator_clut_editor_mesh) << (*decorator_scalar_color_map_mesh);
decorator_clut_editor_mesh->setCanvas(view);
decorator_clut_editor_mesh->setData(this->data_mesh);
decorator_clut_editor_mesh->render();
when the field displayed is updated in the application, the color bar (and the color_function) should be updated.