"unconnected" block sensor (tells us what blocks were placed when outside of build mode)

[Poodleinacan]

I'm presently building a rather large ship... but sadly, I can't really make my ship rotate (it "bumps" on itself) at full speed. If only we could see what blocks weren't placed on the ship while not in build mode, it would make things easier to fix errors.

The "locator" (not an actual object... more the game telling us the error we did) would take effect while in build mode, and highlight the object that was placed while outside of build mode in a certain color.