For skins using the UIS1 format, a new series of parameters allow far greater flexibility in the style of frame borders that you can use.

[Borders]
ShapeFrameCount = number of images in the shape bitmaps.

Each 'row' is the height same height as the titlebar image (linked to the titlebar caption height)
Then we have the 2 images (width of each can be different.
Heights must be = shapeFrameCount * height of each titlebar image row)

ShapeLeftImage = crux_remake\rgn.bmp
ShapeRightImage = crux_remake\rgn2.bmp

Then we tell WB which 'row' to use for each state. There are a number of options. 0 would be the first row, 1 = 2nd, 2 = 3rd etc

ShapeNormalActiveFrame =
ShapeNormalInactiveFrame =
ShapeNormalDisabledFrame =
ShapeMDIActiveFrame =
ShapeMDIInactiveFrame =
ShapeMDIDisabledFrame =
ShapeToolActiveFrame =
ShapeToolInactiveFrame =
ShapeToolDisabledFrame =
ShapeNonSizableActiveFrame =
ShapeNonSizableInactiveFrame =
ShapeNonSizableDisabledFrame =
ShapeNonSizableToolActiveFrame =
ShapeNonSizableToolInactiveFrame =
ShapeNonSizableToolDisabledFrame =

Basically WB allows you to have different shapes for 15 different window styles / states.
Example bits to add to the UIS file of a UIS1+ skin

; modify the path here obviously!
ShapeLeftImage = crux_remake\rgn.bmp
ShapeRightImage = crux_remake\rgn2.bmp
ShapeNormalActiveFrame = 0
ShapeNormalInActiveFrame = 1
ShapeFrameCount= 5