- Have two or three windows in a workspace, all minimized
- Go to Activities, you will see the content of all the minimized windows (cool)
- Go back to the desktop with Esc or by clicking on some empty space in the desktop window
- You will see an animation of all the windows rearranging as if they weren't minimized, then they will suddenly disappear (go back to minimized mode) when the animation finishes.

There should probably be an animation which minimizes the windows when going out of the Activities mode .
Note that this also applies if one of your minimized windows is fullscreen and one is not (e.g. Firefox and a terminal of the default size), and you click on the unminimized one; the fullscreen window will be rearranged as if it wasn't minimized and will disappear suddenly at the end.