Groups are useful for arranging different operations in a single set. Groups may also define the following properties that can be overridden by any nested operation:
- borderColor: defines the color of the shape's outline
- borderWidth: defines the thickness of the shape's outline
- fill: defines the color, paint or gradient to fill the shape's content
- opacity: controls how much of the group is visible, value must be in the range 0..1, default is 1.
Borders and fill are passed to each children.
Border and fill is overridden by one child.