prefab 初始化时, child node的位置位0?

Creator 2.x
#1

//加载prefab

        var self = this;
        cc.loader.loadRes("prefab/dialog", function (err, prefab) {
            let dialog = cc.instantiate(prefab);
            dialog.getComponent("Dialog").show2(message, left, right, callback);
            let canvas = cc.director.getScene().getChildByName('Canvas');
            canvas.addChild(dialog);            
        });

//prefab关联了一个Script Dialog

cc.Class({
    extends: cc.Component,

    properties: {
        message : cc.Label,
        left : cc.Button,
        right : cc.Button,
        rightPos : 0,
    },

    // use this for initialization
    onLoad: function () {
        this.rightPos = this.right.node.position;      //这个position 为0, 为什么, Button在编辑器中查看都不为0啊,
    },
#2

这个应该是因为它本来 position 就是 0