title: WS_EX_COMPOSITED and scrollbar not drawing whilst being dragged
body: <p>I have a form that has many  custom controls on that had a terrible flicker, I found the following code (here on stackoverflow whilst searching for a solution, <a href="https://stackoverflow.com/questions/2612487/how-to-fix-the-flickering-in-user-controls">How to fix the flickering in User controls</a>
  or <a href="https://stackoverflow.com/questions/3718380/winforms-double-buffering">Winforms Double Buffering</a> posted by Hans Passant) which fixed the flicker</p>
  
  <pre><code>protected override CreateParams CreateParams
  {
      get
      {
          CreateParams cp = base.CreateParams;
          cp.ExStyle |= 0x02000000;  // Turn on WS_EX_COMPOSITED
          return cp;
      }
  }
  </code></pre>
  
  <p>However, now if I click the position bar on the scrollbar, the position bar stays fixed, until I let go of the mouse button.</p>
  
  <p>Is there a way to have the scroll position bar update whilst being dragged and not have flicker on the controls?</p>
  
  <p>Many thanks</p>