This window frame looks like it is swinging back and forth. But it’s not a window at all, and it is actually rotating in complete circles!
The window frame is really a flat card with a “picture” of a window painted an each side. The card is shaped like a trapezoid, and made to look like a real window in 3D. Even though the window seems to pause and swing back, it is actually swinging all the way around. There is no pause.