New minecraft version. (1.15)

[LO1ZB]

We don't want invisible, we need to be able to visually inspect where the block is. And sign is not good because it cannot be placed mid-air. I was thinking about the new Barrier block, I seem to recall that it was possible to view it somehow (when you have another barrier block in hand, perhaps?) but can't find the info anymore. It'd be perfect otherwise - is translucent, so grass won't revert to dirt under it, and can be toggled visible / invisible (?).

You can see the barrier block only in creative mode.