I'm sorry, but I can't really see what's so Plusy in it apart from the cropped logos.
To be good it should match most of MP! Preferences GUI's, And the titlebar should have some detailed gfx, like the water-effect-like background. It's difficult to do, because it can't get stretched, but it would be interesting on one of the edges. The taskbar should also have MP! details, like a shaded MP! logo or other things...
Just my few suggestions, let me know if you want some more
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