public void execute() {
startIndex = oldContainer.getChildren().indexOf(child);
oldContainer.removeChild(child);
if (after != null) {
destIndex = newContainer.getChildren().indexOf(after);
newContainer.addChild(child, destIndex);
} else {
newContainer.addChild(child);
}
}
public void undo() {
newContainer.removeChild(child);
oldContainer.addChild(child, startIndex);
}