Using "Custom Move / Resize Window" to Maximize Window Vertically

What do you mean "doesn't really work"?
In my case It doesn't move or resize at all.
(I'm also using 1 external monitor)

Not sure where the origin is, can't even test because it doesn't move.
And couldn't find doc page too.

P.S. I hope this other poor guy could find a use from this thread, maybe.