title: Form.Invoke freezes the UI
body: <p>I have been googling around for about an hour, and I still don't found any solution.</p>
  
  <p>I simply try to set the maximum value of a progressbar from another thread. So I found the Control.Invoke method. I've been going ahead and implement it:</p>
  
  <p><img src="https://i.stack.imgur.com/Sdfoy.png" alt="enter image description here"></p>
  
  <p>Now, when I debug my App it simply stucks at the <code>this.Invoke</code> line. The UI comes up, and it is frozen. So I was going ahead and google that out, and it told me to use <code>this.BeginInvoke()</code>. I implemented it, and I was fine, the UI don't freeze.
  Thats quiet nice, but in fact the maximum value of my progress bar didn't change :(</p>
  
  <p>What am I doing wrong?</p>
  
  <p>EDIT: Maybe that helps: I am using <code>Parallel.Invoke();</code> to manage my thread ...</p>