For MITK properties should be documented what they are doing.
Currently, there are some "weird" properties. For instance, "use color" seems to decide whether a lookup-table is used for rendering or the color which can be set to the node on right click. However, by default the lookup-table is set to standard CT gray values and if you disable the property "use color" the former gray image becomes colored, because now a default RGB color lookup-table will be used. As a consequence, the behavior of this property is really confusing for new users and should be documented well (and probably renamed).
An other example is this documentation from the mitkImageMapperGL2D in line 73 " "in plane resample extent by geometry": (BoolProperty) Do it or not".
Furthermore, we should precisely define the desired behavior of properties if they are used in combination with others. There are huge code parts to act according to the properties but we have no document which actually defines what should happened.