AnchorToCorners

using UnityEditor;
using UnityEngine;


using System.Collections;
using System.IO;
public class AnchorToCorners : MonoBehaviour
{
        [MenuItem("Custom Editor Tools/Anchors to Corners %[")]
        static void AnchorsToCorners()
        {
                RectTransform t = Selection.activeTransform as RectTransform;
                RectTransform pt = Selection.activeTransform.parent as RectTransform;

                if (t == null || pt == null)
                        return;

                Vector2 newAnchorsMin = new Vector2(t.anchorMin.x + t.offsetMin.x / pt.rect.width,
                                            t.anchorMin.y + t.offsetMin.y / pt.rect.height);
                Vector2 newAnchorsMax = new Vector2(t.anchorMax.x + t.offsetMax.x / pt.rect.width,
                                            t.anchorMax.y + t.offsetMax.y / pt.rect.height);

                t.anchorMin = newAnchorsMin;
                t.anchorMax = newAnchorsMax;
                t.offsetMin = t.offsetMax = new Vector2(0, 0);
        }

        [MenuItem("Custom Editor Tools/Corners to Anchors %]")]
        static void CornersToAnchors()
        {
                RectTransform t = Selection.activeTransform as RectTransform;

                if (t == null)
                        return;

                t.offsetMin = t.offsetMax = new Vector2(0, 0);
        }

        [MenuItem("Custom Editor Tools/Add Padding")]
        static void AddPadding()
        {
                foreach (var activeTransform in Selection.transforms) {

                        RectTransform t = activeTransform as RectTransform;
                        if (t == null)
                                return;

                        t.anchorMin = new Vector2(0, 0);
                        t.anchorMax = new Vector2(1, 1);
                        var padding = 5;
                        t.offsetMin = new Vector2(padding, padding);
                        t.offsetMax = new Vector2(-padding, -padding);
                }
        }

}