Moviestorm is a complex bit of software - we (I'm) constantly fighting requests to add more to the interface, to keep it as simple as possible for the n00b. One of the techniques for this is only showing users options when they are applicable.
So for example we hope to only show the "add doors" or "paint walls" options once users click on a wall that they've already created. The latest move in this direction is an experimental widget for moving marks around the set.
Most apps show this widget in 3D, but this has the disadvantage that the widget isn't under the mouse when the drag is finished, so continuing the drag isn't fluent. Putting it in 2D and making it appear on demand should be a cleaner solution, but as with most of UI design, we won't know if it's the right way until we see people using it.