The Camera View toolbar Display options 
let you configure elements of the Viewer window display.
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.
When the Selective Redraw option is activated 
it refreshes the current scene in the Viewer window without updating the operations in any other window.
lets you lock and magnify the current camera view.