To reproduce:

1. Open the MITK workbench and load an image and
2. Right-click on the level-window slider and select Set maximum window. Observe how the level window / image intensity changes.
3. Right-click on the level-window slider and select Default level-window. The level window / image intensity is reset to original.
4. Right-click on the level-window slider and select either Use whole image grey values or Use optimized level-window. Observe how the level window / image intensity changes.
5. Right-click on the level-window slider and select either Set maximum window or Default level-window. The level window / image intensity does not change anymore to the values of (2) or (3).