This works:
(Get-Host).UI.RawUI
$a = (Get-Host).UI.RawUI
$a.BackgroundColor = "white"
$a.ForegroundColor = "black"
$size = (Get-Host).UI.RawUI.WindowSize
$size.Width = 80
$size.Height = 30
(Get-Host).UI.RawUI.WindowSize = $size
But this doesn't work, and I am not sure how to make it work:
$position = (Get-Host).UI.RawUI.Windowposition
$position.X = 0
$position.Y = 30
(Get-Host).UI.RawUI.Windowposition = $position
The error I get is strange. It complains about "buffer" when I am trying to set external window position:
Exception setting "WindowPosition": "Cannot use the
specified Window X (column) position because it extends
past the width of the screen buffer. Specify another X
position, starting with 0 as the left most column of
the buffer.