The stretch fence command should display the fence content dynamically as the fence is being dragged around. Just as it does with the other Manipulate Fence commands. In V8i it only shows the fence itself being moved, not its content. Manipulated content is shown when done manipulating.
Mostly Lines, Line Strings, Shapes, Complex Shapes. Sometimes those are in a Cell
This is a great idea that we will consider for the future. What type of geometry are you using when using the tool?