If User Security is not enabled, to protect a diagram against inadvertent changes such as moving or resizing elements, you can lock the diagram. If you or any other users select any object on a locked diagram, the object's border or outline displays in red.
Right-click on the background of open diagram | Lock Diagram
- This does not apply in the Corporate, Unified and Ultimate editions if User Security is enabled; in this case, see the Lock Model Elements topic
- To unlock the diagram, select the 'Lock Diagram' menu option again