setLayoutIndex method
Implementation
void setLayoutIndex(int layout) {
  assert(_currentLayout >= 0 && _currentLayout < layouts.length,
      "Invalid layout index");
  _currentLayout = layout;
  update();
}void setLayoutIndex(int layout) {
  assert(_currentLayout >= 0 && _currentLayout < layouts.length,
      "Invalid layout index");
  _currentLayout = layout;
  update();
}