Locked objects do not stay locked after saving and exiting, which makes the locking feature quite limited in its usefulness. It would be more useful if an object or group of objects stay locked after saving, until you unlock it. More than once I've moved a mountain when aiming for a plant. And also it's hard to deselect an item without having to select another item or the sky. And this also causes me to select land then move it by mistake. Deselect an item is another issue.
Locked objects should save as locked