The Camera View toolbar let you configure elements of the Viewer window display.
The Ruler option enables you to measure and display the distance between two objects.
To view the trajectory for any animated object, select the object, and click the Trajectories button . Expand the Trajectories menu to view the Trajectories menu options.
The 2D Magnifier option lets you lock and magnify the current camera view.
When the Selective Redraw option is activated it refreshes the current scene in the Viewer window without updating the operations in any other window.