This is a variation of the Plastic decorations. The difference is that the border is thinner, and that the buttons on the top right are colourized when hovered over.
This also includes a blue colour scheme.
Of course, when Colorize frames is turned off, these decorations will look gray, just like the original Plastic decorations.
Kudos to Jon Clarke for some great artwork!
Try the button animation with fade, and use #585858 as the active colour.