title: Cannot add a tooltip to appear when the mouse hovers to a unity EditorGUILayout.Popup()
body: <p>I have a quite complex GUI in unity whit public override void OnInspectorGUI().
  For all of my normal fieds I can add a tooltip with the header: Tooltip[("")] in the class itself.
  However, I need a dynamic dropdown list that needs to be updated with the number of elements of a list.
  I works great. Find the code of the custom editor script for the dropdown list:</p>
  
  <pre><code>        string[] options = new string[movParamsListSize];
          for (int i = 0; i &lt; movParamsListSize; i++)
              options[i] = i.ToString();
  
          Rect r = EditorGUILayout.BeginHorizontal();
          movStepToMoveTo.intValue = EditorGUILayout.Popup("movementStepToMoveTo",
          movStepToMoveTo.intValue, options, EditorStyles.popup);
          EditorGUILayout.EndHorizontal();
  </code></pre>
  
  <p>Find also a screenShot:</p>
  
  <p><a href="https://i.stack.imgur.com/xVT1b.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/xVT1b.png" alt="enter image description here"></a></p>
  
  <p>My problem is that I tried with all the overloaded functions of the EditorGUILayout.Popup() function (image below from the metadata) and cannot figure out how to add a tooltip when the mouse hovers to this control. </p>
  
  <p><a href="https://i.stack.imgur.com/cMNSf.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/cMNSf.png" alt="enter image description here"></a> </p>
  
  <p>Any help is much apprecciated. Many thanks</p>