another suggestion from me 🙂 When I “lock” an object so it isn’t movable or selectable any more, it still reacts to clicks. When I click on it (usually I click on a title-level full-page background image by accident) it steals the focus, jumps to the title level, brings the image in front and generally disrupts my work. I’d prefer locked objects to be NOT SELECTABLE AT ALL other than in the Title Explorer tree, or maybe also while holding a modifier key.
This way I can lock most title-level images, background objects, full-page photos etc. and only bother with the stuff I’m currently working on.