The dragging idea goes like this. You could create operation objects like a smoothing object. The object would be the child of a parent object like a scene object or some other child to the scene object To apply smoothing to an object you just put the object in as a child to the smoothing operation object. You can add a material to the smoothing operation so it's title might read smoothing AND color(1 0 0) then anything that becomes the child of this object would be smoothed and turned red. You could then drop another operation object into the smoothing AND color(1 0 0) object that might be an lathe path operation for example, the user could choose to bind a curve to this object and lathe it.

One of the really powerful features to this type of setup is that you can pull objects out of the parent operation levels and replace them with other objects or you could pull operations out of the parent level operations and replace them with other operations. So you could create an object like a rope and if you want to change the shape of the rope you swap out the profile curve for another curve. Or if you want to change the shape of how the rope is coiled you replace the lathe path with another lathe path. The user doesn't have to continue to redue the object from scratch reguardless of how long ago they created the original rope object.

Another very nice feature of this paradigm is an intrinsic history that forms. You can follow the history and modify it anywhere in the hierarchy.

This type of hierarchy control is easiest to implament in an object oriented language. You're using visual c++ I think, right?

Let me know if I'm leaving something important out or I'm just not explaining the idea well.