title: UIView.ZoomAndCenterRectangle() only works correctly when called twice
body: <p>I've encountered some odd behavior in Revit 2018.2 when calling the UIView.ZoomAndCenterRectangle() method. The scenario is that I've just created a new 3D view using 3DView.CreateIsometric() and have also set that 3DView as the UIDocument's ActiveView. Following those actions, calling UIView.ZoomAndCenterRectangle() just once doesn't seem to work at all. However, If a call it a second time immediately after the first, the view zooms properly!</p>
  
  <p>My initial thought was that the first ZoomAndCenter call may have been taking up just enough time for the 3DView to fully generate and begin receiving calls, although that seems unlikely because I was under the impression that Revit external commands run entirely synchronously. Regardless, I tried the following code, which results in a tangible delay of 500ms:</p>
  
  <pre><code>int val = 0;
  for(int i = 0; i &lt; 500000000; i++)
  {
      val += i;
  }
  
  uiView.ZoomAndCenterRectangle(max, min);
  //uiView.ZoomAndCenterRectangle(max, min);
  </code></pre>
  
  <p>But that still didn't work... so it seems that for some odd reason, you really have to run the call twice in order for it to execute:</p>
  
  <pre><code>uiView.ZoomAndCenterRectangle(max, min);
  uiView.ZoomAndCenterRectangle(max, min);
  </code></pre>
  
  <p>Am I missing something!!??</p>