Take a window to background

I am looking for a way to take the front window all the way back behind other windows, so that it becomes the last one in the stack (the kind of thing Alt-F3 normally does in X-server). Getting kinda desperate though find it hard to believe a simple thing like this is missing … :frowning:
Any ideas?

I follow this forum fairly closely, and I don’t recall ever seeing a way to do that.