You can't place widgets on a layer different than the UIPanel that manages them.

http://blog.csdn.net/chenggong2dm/article/details/39341823

运行NGUI做的背包的时候，报警告：

"You can't place widgets on a layer different than the UIPanel that manages them."
"If you want to move widgets to a different layer, parent them to a new panel instead."

点开代码看了一下NGUI的源码，是这样写的：

public void CheckLayer ()
{
    if (panel != null && panel.gameObject.layer != gameObject.layer)
    {
        Debug.LogWarning("You can't place widgets on a layer different than the UIPanel that manages them.\n" +
            "If you want to move widgets to a different layer, parent them to a new panel instead.", this);
        gameObject.layer = panel.gameObject.layer;
    }
}

看了一下很简单，就是检查一下层号是否相同，如果不同，报个警告，并强制同层。

解决办法：

1，如果背包里的物品都是预制，那么保证预制的层（Layer），与背包一致。

2，也可以在代码里用 the_gameobj.layer = n ; (n为int)  来动态的保持层一致性。