Comment 7 for bug 1714286

Maybe a workaround, using dconf-editor, browse to /org/gnome/shell/extensions/dash-to-dock

There change middle-click-action to 'minimize'
and
shift-middle-click-action to 'launch'

Now a middle click minimizes current running window and shift middle click opens a new window ( if one is already running ).

To get closer to Unity, I also was suggested to change scroll-action to 'cycle-windows'.

And well I begin to little enjoy 17.10.