Slice Input Box & Depth Finder Tool

So my idea is simple, add a tool like an depth picker like a color picker in most programs, click the tool then click a block ( or just hover over it, even better) and it displays what depth that block is at, then you can type into the slice tool exactly what depth you want to be at. no more spamming up and down and waiting for the load lagg. 3 clicks type in numbers and hit enter. done.