title: Issue with drag and drop
body: <p>I use the following code to drag and drop a file into a c# winforms application. The issue I have is that the DragDrop event handler takes a while, and during this time I can't use the window from which I dragged the file. How can this be fixed?</p>
  
  <pre><code>private void FormMain_DragDrop(object sender, DragEventArgs e)
  {
      string[] s = (string[])e.Data.GetData(DataFormats.FileDrop, false);
      // do some long operation
  }
  
  private void FormMain_DragEnter(object sender, DragEventArgs e)
  {
  if (e.Data.GetDataPresent(DataFormats.FileDrop))
      e.Effect = DragDropEffects.All;
  else
      e.Effect = DragDropEffects.None;
  }
  </code></pre>