title: Add a document type to a Mac OS X Project
body: <p>My Mac application is not a document based application. That means you can have only one window open and you do not notice the saving of the data to a file in the library.</p>
  
  <p>But now I want to import and export data. </p>
  
  <p>I found it was not that hard, and the importing and exporting works well. </p>
  
  <p>BUT: Not good enough. When you see the exported file in finder, you see it as an unknown file. And if you try to open it, you get the message that no application, not even my app can open it. You have to click "Import" In the App.</p>
  
  <p>I want that you can see the file being part of my Application.</p>
  
  <p>And if you click it, the application should show up and ask you if you want to import. I googled for it and I searched the preferences, but I did not find anything. Can you help me?</p>