title: Mouse clicks aren't recognized when I build Unity game
body: <p><strong>EDIT :</strong> Apparently when I select Windowed, the buttons work. Why is this? Why doesn't it work without that box selected?</p>
  
  <p>I created a game in Unity and everything works fine in Unity itself. When I build and run the game, my buttons no longer recognize my mouse clicks. Why is this?</p>
  
  <p>This is a basic pong game. I don't know why it would work in Unity and not outside of Unity if it was the code but here is the code.</p>
  
  <p><strong>Code :</strong></p>
  
  <p>paddle script:</p>
  
  <pre><code>using UnityEngine;
  using System.Collections;
  
  public class paddle : MonoBehaviour {
  
      public float paddleSpeed = 1;
      public Vector3 playerPos = new Vector3(0,0,0);
  
      // Update is called once per frame
      void Update () {
          float yPos = gameObject.transform.position.y + (Input.GetAxis ("Vertical") * paddleSpeed);
          playerPos = new Vector3 (-20,Mathf.Clamp(yPos, -13F,13F),0);
          gameObject.transform.position = playerPos;
      }
  }
  </code></pre>
  
  <p>ball script:</p>
  
  <pre><code>using UnityEngine;
  using System.Collections;
  
  public class Ball : MonoBehaviour {
  
      public float ballVelocity = 1500;
  
      private Rigidbody rb;
      private bool isPlay; //false by default
      int randInt; //random ball directon when game begins
  
      // Use this for initialization
      void Awake () {
          rb = gameObject.GetComponent&lt;Rigidbody&gt; ();
          randInt = Random.Range (1,3);
      }
  
      // Update is called once per frame
      void Update () {
          if(Input.GetMouseButton(0) == true &amp;&amp; isPlay == false){
              transform.parent = null;
              isPlay = true;
              rb.isKinematic = false;
              if(randInt == 1){
                  rb.AddForce(new Vector3(ballVelocity,ballVelocity,0));
              }
              if(randInt == 2){
                  rb.AddForce(new Vector3(-ballVelocity,-ballVelocity,0));
              }
          }
      }
  }
  </code></pre>
  
  <p>enemy script: </p>
  
  <pre><code>using UnityEngine;
  using System.Collections;
  
  public class Enemy : MonoBehaviour {
  
      public float speed = 8;
      private Vector3 targetPos;
      private Vector3 playerPos;
      private GameObject ballObj;
  
      // Use this for initialization
      void Start () {
  
      }
  
      // Update is called once per frame
      void Update () {
          ballObj = GameObject.FindGameObjectWithTag ("ball");
          if (ballObj != null) {
              targetPos = Vector3.Lerp (gameObject.transform.position, ballObj.transform.position, Time.deltaTime * speed);
              playerPos = new Vector3 (-20, Mathf.Clamp (targetPos.y, -13F, 13F), 0);
              gameObject.transform.position = new Vector3 (20, playerPos.y, 0);
          }
      }
  }
  </code></pre>
  
  <p>score script:</p>
  
  <pre><code>using UnityEngine;
  using System.Collections;
  
  public class Score : MonoBehaviour {
  
  
  
  public TextMesh currScore;
      public GameObject ballPref;
      public Transform paddleObj;
  
      GameObject ball;
      private int score;
  
      // Use this for initialization
      void Start () {
  
      }
  
      // Update is called once per frame
      void Update () {
          ball = GameObject.FindGameObjectWithTag("ball");
          currScore.text = "" + score;
          }
      void OnTriggerEnter(Collider other) {
          if(other.tag == "ball"){
              score += 1;
              Destroy(ball);
              (Instantiate(ballPref, new Vector3(paddleObj.transform.position.x + 1, paddleObj.transform.position.y,0), Quaternion.identity) as GameObject).transform.parent = paddleObj;
          }
      }
  }
  </code></pre>
  
  <p>title screen script:</p>
  
  <pre><code>#pragma strict
  
  function Start () {
  
  }
  
  function Update () {
  
  }
  
  function StartGame () {
      Application.LoadLevel("Main");
  }
  
  function ExitGame () {
      Application.Quit();
  }
  </code></pre>