The planar Figure module has some proprietary mechanism using properties to reflect the differing item states, like unselected, hovering, selected.

The colors are encoded like planarfigure.hovering.line.color or planarfigure.selected.annotationtext.opacity

(see mitk::PlanarFigureMapper2D::InitializeDefaultPlanarFigureProperties(), line 447)

We should discuss if such a standardized mechanism would be helpful at a somehow higher level, like mitk::BaseData.

This could help for a simple interaction with objects like segmentations (binary images), also.