When the rotation of the window is observed, the window appears to rotate through less than 180 degrees, though the exact amount of travel that is perceived varies with the dimensions of the trapezoid. It seems that the rotation stops momentarily and reverses its direction.
When the window's rotation is observed, it appears to rotate less than 180 degrees, though the precise amount of movement perceived varies depending on the dimensions of the trapezoid. It seems that the rotation momentarily stops and reverses direction.