public GameObject PrefabButton; // Attached the colored Button.prefab
public GameObject TargetPanel; // Attached the Panel from the UI Root Hirachie
void Start ()
{
GameObject PrefabSpawnButton = NGUITools.AddChild(TargetPanel, PrefabButton) as GameObject;
// Till this point everything goes well. But the Anchors are on type : none
PrefabSpawnButton.GetComponent<UISprite>().topAnchor.target = TargetPanel.transform;
PrefabSpawnButton.GetComponent<UISprite>().bottomAnchor.target = TargetPanel.transform;
PrefabSpawnButton.GetComponent<UISprite>().leftAnchor.target = TargetPanel.transform;
PrefabSpawnButton.GetComponent<UISprite>().rightAnchor.target = TargetPanel.transform;
PrefabSpawnButton.GetComponent<UISprite>().topAnchor.absolute = -60;
PrefabSpawnButton.GetComponent<UISprite>().bottomAnchor.absolute = -124;
PrefabSpawnButton.GetComponent<UISprite>().leftAnchor.absolute = 20;
PrefabSpawnButton.GetComponent<UISprite>().rightAnchor.absolute = 84;
}