title: How to draw sprites at the right position
body: <p>I'm getting crazy trying to understand libgdx's system coordinates.
  I've made a grid of containers (classes that extend Container, and have a reference to their screen position with a Vector2) in the center of my stage. Now, when the user clicks on any of these slots, he can add an actor (which has a Sprite) to it. The first thing that my Actors need to do is initialize his Sprite.</p>
  
  <p>The first thing to which a normal guy thiks is "ok, i have to set the position of the Sprite. I can take the reference to the position (Vector2) of its Container and use that position for my Sprite"</p>
  
  <p>So, i did that:</p>
  
  <pre><code>@Override
  protected void initActor() {
      Texture texture = new Texture(Gdx.files.internal("blue_square.png"));
      sprite = new Sprite(texture, texture.getWidth(), texture.getHeight());
      sprite.setPosition(getSlotActor().getPosition().x, getSlotActor().getPosition().y);
  }
  </code></pre>
  
  <p>My grid is 5x5. If i click on the middle row, the Sprite happens to be in the right position, if i click on the 2nd row, it happears on the fourth one, if i click on the first row it happears on the fifth one, if i click on the fifth one it happears on the first one and so on...</p>
  
  <p>I can't understand this behavior..</p>