title: Updating progress bar in petrel from another thread
body: <p>I am trying to develop a multithreaded plugin in petrel where my algorithm runs in 2 separate threads. The plugin seems to work fine except I cant find any method to update the progress bar.</p>
  
  <p>using Invoke does not update the progress bar(c# progress bar) and my UI completely freezes during execution.</p>
  
  <p>Is there any way to update the progress bar (Either petrel progress or standard progresss bar) from another thread when the algo is running?</p>
  
  <p>Thanks</p>