Properties for various classes have stacked categories. Each item might have many various Properties. On Volkswagen environment I have Functional Areas, which has 12 different Categories and each holds minimum 6-7 properties. It is around 80 different properties. I would suggest to move this selected items view part somewhere else. Leave Spatial containment tree in any side, because we need this tree to be always visible and as big as possible. In some models there are so many items, that it might be hard to scroll up or down each time and bigger tree view would help here. Then properties view dialog or window could be separately placed in the other side of the screen and as well with possibility to make it big and allow to see as much stacked categories as possible. This way user could see the required information about selected item very fast and without the need of scrolling.