Simple inspector to use along with DOTween for implementing sliding GUI elements in Unity 5.

SlideTween.cs

using UnityEngine;
using System.Collections;
using DG.Tweening;

// BOA
public class SlideTween : MonoBehaviour
{
    public enum Position { OutsideTop, OutsideBottom, OutsideLeft, OutsideRight, Center, InsideTop, InsideBottom, InsideLeft, InsideRight };
    public Position enterPoint;
    public Position targetPoint;
    public Position exitPoint;
    public DG.Tweening.Ease enterEase;
    public DG.Tweening.Ease exitEase;

    public float enterDuration = 1f;
    public float exitDuration = 1f;
    public float exitTimeout = 0f;
    public bool disableAfterExit = true;
    public bool bringToFront = true;

    private Vector3 endPos;

    public void PlayTween()
    {
        // Initializes DOTween
        DOTween.Init(false, true, LogBehaviour.ErrorsOnly);
        // Activate gameObject if it's not already
        gameObject.SetActive(true);
        // Sets initial position
        transform.position = GetPosition(enterPoint);
        // Stores the target posigion
        endPos = GetPosition(targetPoint);
        // If "Bring to front" is enabled, set the gameObject as last sibling
        if (bringToFront)
        {
            // Brings the gameObject to the front of layer
            gameObject.transform.SetAsLastSibling();
        }
        // If the exitTimout is set, starts a coroutine
        if (exitTimeout > 0f && gameObject.activeSelf) StartCoroutine(Show(exitTimeout));
        // Or simply displays the gameObject without the exitTimeout
        else Show(enterEase);
    }

    IEnumerator Show(float timeout)
    {
        MoveIn();
        yield return new WaitForSeconds(timeout);
        MoveOut();
    }

    void Show(DG.Tweening.Ease enterEase)
    {
        MoveIn();
    }

    void MoveIn()
    {
        // Tweens the gameobject from the start point to the target point
        transform.DOMove(endPos, enterDuration).SetEase(enterEase);
    }

    IEnumerator Exit()
    {
        // Tweens the gameobject to the end point from it's current position
        transform.DOMove(GetPosition(exitPoint), exitDuration).SetEase(exitEase);
        // If "Disable after exit" is on, deactivate the gameobject
        if (disableAfterExit)
        {
            yield return new WaitForSeconds(exitDuration);
            gameObject.SetActive(false);
        }
    }

    public void MoveOut()
    {
        if (gameObject.activeSelf)
        {
            StartCoroutine(Exit());
        }
    }

    public Vector3 GetPosition(Position position) {
        // Get gameobject's rect transform
        RectTransform rt = gameObject.GetComponent<RectTransform>();
        // Get gameobject's current width and height
        Vector2 size = Vector2.Scale(rt.sizeDelta, transform.lossyScale);
        // Get current screen size
        Vector3 screenSize = Camera.main.ViewportToWorldPoint(new Vector3(0, 1, 0));

        // Set screen positions
        Vector3 screenOutTop = new Vector3(endPos.x, screenSize.y + size.y / 2, endPos.z);
        Vector3 screenOutBottom = new Vector3(endPos.x, -screenSize.y - size.y / 2, endPos.z);
        Vector3 screenOutLeft = new Vector3(screenSize.x - size.x / 2, endPos.y, endPos.z);
        Vector3 screenOutRight = new Vector3(-screenSize.x + size.x / 2, endPos.y, endPos.z);

        Vector3 screenInTop = new Vector3(endPos.x, screenSize.y - size.y / 2, endPos.z);
        Vector3 screenInBottom = new Vector3(endPos.x, -screenSize.y + size.y / 2, endPos.z);
        Vector3 screenInLeft = new Vector3(screenSize.x + size.x / 2, endPos.y, endPos.z);
        Vector3 screenInRight = new Vector3(-screenSize.x - size.x / 2, endPos.y, endPos.z);

        Vector3 pos;

        // Find the start position
        switch (position) {
            // Outside positions
            case Position.OutsideTop: pos = screenOutTop; break;
            case Position.OutsideBottom: pos = screenOutBottom; break;
            case Position.OutsideLeft: pos = screenOutLeft; break;
            case Position.OutsideRight: pos = screenOutRight; break;
                // Inside positions
            case Position.InsideTop: pos = screenInTop; break;
            case Position.InsideBottom: pos = screenInBottom; break;
            case Position.InsideLeft: pos = screenInLeft; break;
            case Position.InsideRight: pos = screenInRight; break;
                // Default position
            default: pos = Vector3.zero; break;
        }

        // Returns the world position
        return pos;
    }
}