pair-virtual->viewport -- Convert a pair point from virtual to viewport coordinates.
window-center-middle -- Return pair (viewport-x .
window-center-top -- Return a pair (X .
window-center-bottom -- Return a pair (X .
window-left-middle -- Return a pair (X .
window-right-middle -- Return a pair (X .
window-left-top -- Return a pair (X .
window-left-bottom -- Return a pair (X .
window-right-top -- Return a pair (X .
window-right-bottom -- Return a pair (X .
window-viewport-position-of -- Return a list (X Y) that is the viewport position of the SYM part of WIN.