title: pgAdmin 4.7 displays blank popup screen on startup
body: <p>I've just installed latest pgAdmin (4.7) and whenever I start it up I get this strange blank popup which I can not remove:
  <a href="https://i.stack.imgur.com/RbxAP.png" rel="noreferrer"><img src="https://i.stack.imgur.com/RbxAP.png" alt="enter image description here"></a></p>
  
  <p>I can use the application just fine I just need to move that empty window to the side which is annoying.
  I'm using Firefox version 67 (64bit).</p>