Allow the user to hide / show & lock and unlock objects {parts|groups(unsupported now|steps|models} in the "File Contents" pane. This would add two columns with small icons which status on click and would allow the user to hide/show the object or lock/unlock the object in the respective column. Both features would enable faster editing and would prevent the user from making unintentional mistakes.
Hide - Hides the current object - all references are hidden as well
Show - Un-hides the object - all references are visible
Lock - prevents the object from having colors / coordinate changes (still selectable for copy / paste)
Unlock - unlocks the object