Yep, just what Dan said. Like in Photoshop, you can control the visibility and editability of each layer.
I'm a little confused. Can't this be done already? Lock a track and it becomes impossible to edit. Click on a non-locked track and it's notes come to the top. Click on the Show/Hide track icon and its data disappears.
The only way I can make a locked track's notes come to the top is by clicking on the locked track's header in the track pane. Clicking on a locked track's notes doesn't do that. if the track is hidden I can't even see the data never mind edit it.
Visibility and edibility is already fully controllable, unless I'm mis-understanding something.