An FFGL mixer that cuts between this layer and the one below the way a relay-switched router used to. The layer's opacity fader is the coil, with pull-in and drop-out hysteresis. The contacts bounce, so the switching frame shows bands of A, black and B at the scanlines where each hit landed. The monitor's PLL has to re-lock, so the new picture rolls and settles. And the open contact is a capacitor, so the unselected picture ghosts through, high-passed.
This demo runs the plugin's shaders in your browser, so it needs JavaScript and WebGL2. The plugin itself, its source and its downloads are on its repository.