Drag the cards pick a card up, drop it on a zone: movie.pick and variables

A card is a group named card0… whose place is two variables; movie.pick(x, y, { only: ['card0', …] }) says which card is taken and movie.pick(cx, cy, { only: ['done', 'later'] }) which zone lies under its middle. A zone's glow is a layer whose alpha is a variable. The page listens on the window while a card is held, so the pointer may leave the picture.