title: RectTransform coordinates according to TextMesh Pro text size
body: <p>I'm trying to create an InputField (TextMesh Pro) with a dynamic (its text content may vary) prefix.
  This spectacular image should explain the goal.</p>
  
  <p><a href="https://imgur.com/a/qx1eXOa" rel="nofollow noreferrer">https://imgur.com/a/qx1eXOa</a></p>
  
  <p>So I set a TextMeshPro text to use as Prefix, and by script I was trying to "move" the TextArea accordingly.
  The fact is, TextArea is a RectTransform, and I'm operating in a ScreenSpace render mode.</p>
  
  <p>I was trying like this:</p>
  
  <pre><code>private TextMeshProGUI prefix;
  private RecTransform textArea;
  
  
  public void ChangePrefixTo(string newPrefix)
  {
      float oldWidth = prefix.preferredWidth;
  
      prefix.text = newPrefix;
      float newWidth = prefix.preferredWidth;
  
      Vector2 newPos = new Vector2();
      newPos.x = textArea.position.x + (newWidth - oldWidth);
      newPos.y = textArea.position.y;
  
      textArea.position = newPos;
  }
  </code></pre>
  
  <p>, but the textArea gets shot into the stars.
  How can I map the RectTransform position according to the size of a TextMeshPro text?</p>
  
  <p>Thanks for the help and long live the whales</p>