Currently the level window slider can be used to set the level window of the topmost visible image (in the datamanager). It is also possible to use the context-menu of the level window slider and set the level window for a different data node. However, there is a scenario, where users want to apply the same level window to a set of data nodes, e.g. a set of CT-images. This is, afaik, currently not possible and should be discussed / tackled.