title: How can I use/override PackageProperties in System.IO.Packaging?
body: <p>I know that if you do the following call:</p>
  
  <pre><code>Package package = Package.Open(fileName);
  </code></pre>
  
  <p>a <code>ZipPackage</code> is actually returned since the Package class is abstract.  The package class has a property of type <code>PackageProperties</code>, which I would like to use. The problem is that the extending class must implement the <code>PackageProperties</code> class and <code>ZipPackage</code> apparently does not. <code>PackageProperties</code> is a read only property on <code>ZipPackage</code> and contains all null values.  I cannot extend <code>ZipPackage</code> because it is sealed.  </p>
  
  <p>So short of writing my own implementation of the <code>Package</code> class, is there any way to actually use the <code>PackageProperties</code> class and set values on it?</p>
  
  <p>Info On packaging was found here:<br>
  <a href="http://msdn.microsoft.com/en-us/library/ms569886.aspx" rel="nofollow">http://msdn.microsoft.com/en-us/library/ms569886.aspx</a></p>