ControlGroup.java

class Control {
  void measure();
  void layout(float x, float y, float width, float height);
  void draw();
  void dispatchMouseEvent(MouseEvent event);
}

class ControlGroup {
  List<Control> children;
  
  void measure() {
    for(Control c : children)
      c.measure();
    // measure with children
  }
  
  void layout(float x, float y, float width, float height) {
    super.layout(x, y, width, height);
    for(Control c : children)
      c.layout(x2, y2, width2, height2);
  }

  void draw() {
    super.draw();
    for(Control c : children)
      c.draw();
  }

  void dispatchMouseEvent(MouseEvent event) {
    // fire listeners?
    for(Control c : children)
      c.dispatchMouseEvent(event);
  }
}