Slide out block widget panels

Is it possible to create a slide out block widget panel like the ones has? For example:

If so, any pointers on how one would go about doing this? Are there any tutorials, etc.?



I also found this from the Brackets repo:

It should be, since Brackets is built on CodeMirror. I suspect they define a CSS transition for a line widget element and call changed() on the widget handle when it has finished animating.