use the center of the frame window as gravity point.
keep the current gravity point.
use the center of the frame window's right side as gravity point.
use the center of the frame window's top side as gravity point.
use the right top corner of the frame window as gravity point.
use the left top corner of the frame window as gravity point.
use the center of the frame window's bottom side as gravity point.
use the right bottom corner of the frame window as gravity point.
use the left bottom corner of the frame window as gravity point.
use the left top corner of the client window as gravity point.
use the center of the frame window's left side as gravity point.
Flag used when changing the geometry of a #WnckWindow. This is the gravity point to use as a reference for the new position.