I just recently looked at the widgets screen with MP6 and Midnight Color Scheme added.

On resizing  to a larger screen the Widgets area and available Widgets area shows two columns. As can be seen below.

Resizing one step down it looks like this:

The left Widgets area is really wide and the right Available Widgets are in one long column.

It would be better to wait with changing to one column until the Widgets area is a lot smaller. As having this wide of a Widgets area is just waste of space as I see it.

I would also add a better contrasting border around the Widget Areas:

I added a border of 1px groove and the color #ABBDAB to the div.widgets-liquid-right and div.widgets-holder-wrap.
If you compare to the first screenshot at the beginning of the post to the one right above adding this color creates a better contrast.

But most of MP6 has very little contrast and I believe it would be nice to broaden the contrast in general in MP6.
As it would create a better distinction between the background and the various boxes. As right now boxes blend too much into the background.