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.