title: Update parent activity view before transitioning back to it
body: <p>I have a main activity that launches another activity, let's call it A2.  When A2 finishes loading, it triggers an event that updates the main activity's view. This works great.</p>
  
  <p>The problem is that when I press back or finish() in A2 and it begins the transition animation back to the main activity, the main activity's view doesn't seem to have been redrawn prior to the animation commencing, so as it slides back in it still has the old layout.  When the transition finishes, it updates to what it should be.</p>
  
  <p>Is there a way to force the main activity to invalidate its view or otherwise force it to redraw its view prior to the transition, so that the animation looks nice and smooth?  I have tried <code>invalidate()</code>, but that does not redraw until after the transition.</p>
  
  <p>(To avoid the XY problem: as a part of a complex animation from the main activity to A2, I create and fade in a black overlay view on the main activity.  When A2 onResume()'s, it sends a navigation finished event that causes the main activity to remove the overlay.  When returning from A2, that overlay is still rendered, so it looks like it's transitioning into a black screen until the transition finishes and the view re-renders.)</p>