title: SaveDialog file exist?
body: <p>I use this code to save an avi file. When I create a new file, it's no problem.
   But When I choose an existing file, It does not work and <code>saveFileDialog</code> still shows. </p>
  
  <p>I have set <code>saveDialog.OverwritePrompt</code> and <code>saveDialog.CheckFileExists</code> is true, but it is not ok. If I set <code>saveDialog.OverwritePrompt</code> is false it runs, but it does show overwrite warning</p>
  
  <p>How can I solve this?</p>
  
  <pre><code>SaveFileDialog saveDialog = new SaveFileDialog();
  saveDialog.OverwritePrompt = true;
  DialogResult dgResult = saveDialog.ShowDialog();
  
  if (dgResult == DialogResult.OK)
  {
       exportAvi(saveDialog.FileName);
  }
  </code></pre>