picture-in-picture mode

[HT-7]

Many desktop environments have an "always on top" option, however, celluloid needs to have a "picture in picture" mode which hides everything except the video viewport.

If the mouse hovers over it, playback controls such as the seek bar, play/pause, prev/next and jump back and forth, and a timer become visible.

The picture-in-picture also needs to be resizable and freely movable.