Locking Schematic

On the menu, choose Schematic, Lock Schematic to lock or unlock the Schematic for editing.  If the schematic is locked, a check mark will appear next to the "Lock Schematic" menu item.  Objects on the schematic cannot be added, moved or deleted while it is locked.  A benefit of locking the schematic is that it will prevent you from inadvertently moving a node or link.