when changing a property within the DataManager Property view the changes are shown after performing another action (clicking enter or clicking into another view). This problem seems to be QT4 related.(for more information ask Michi) I just recognized that it is a little bit confusing and it would be better if the property is changed when closing the corresponding property drop down list. Maybe an apply changes button would do as well.
As described above its a bug for discussion so feel free to discuss .. :-)