Information on the structure of the background graphic
The background graphic must be structured in the following manner.
From top to bottom, it must have the following states and they must have exactly the same size:
- Normal
- Hover
- Pressed
- Inactive
- Selected
- Hover when pressed
- Evaluation: selected and the selection is correct
- Evaluation: selected and the selection is wrong
- Evaluation: nothing selected and therefore wrong
- Evaluation: correctly selected nothing
- Sample solution: selected for sample solution
- Sample solution: nothing selected for sample solution

The height and width of the element are automatically adapted to the "Normal" state.