There’s just one little improvement in Witch 2.0.2: To make minimized windows more discernible, their icons are now displayed inside their own little “docks”. (You can edit the border color of those docks in the “Appearance” section of the Witch preference pane.)
Looking back, I really don’t have the slightest idea why I didn’t do it that way in the first place. Once again, Rob Griffiths had to point out the obvious. Thanks, Rob!