Building Layer Tool and lockable layers

Some complex structures are hard to change when multiple layers of pipes/belts are on-top, being able to hide layers of structures (say hide layer -1 and above), would allow easier troubleshooting/rebuilding.
I see this working a little like the layers in photoshop. Hide a layer, lock a layer (to prevent accidental deletion)
It would make underground pipes really appealing, as you could build over them without worry of deleting them by accident when cutting and pasting structures over the top.

Credit to Blottoo for the idea :)

Another suggestion was to just be able to lock individual buildings to prevent destruction.

I'd really like to see this. I like to build compact, and it's really hard to manage the bottom layer of transports when there are buildings on both sides and there are 1-2 layers of transports on top. There have been cases where I had to physically remove the layers on top to be able to work with the bottom layers.