2 Replies
Walt Hamilton

Are you referring to what PowerPoint calls layers; the invisible transparency that every object resides on? In SL the layers are like adding a transparency to an overhead projector. Each of what SL calls a layer can have any number of objects and triggers on it. They have no useful order; they are either hidden, or the most recently shown layer is on the top. 

The description you give sounds like the z-order of objects, and it cannot be changed while the project is playing, only in the development stage.