title: What is the easiest way to upgrade a large C# winforms app to WPF
body: <p>I work on a large C# application (approximately 450,000 lines of code), we constantly have problems with desktop heap and GDI handle leaks. WPF solves these issues, but I don't know what is the best way to upgrade (I expect this is going to take a long time). The application has only a few forms but these can contain many different sets of user-controls which are determined programatically.</p>
  
  <p>This is an internal company app so our release cycles are very short (typically 3 week release cycle).</p>
  
  <p>Is there some gradual upgrade path or do we have to take the hit in one massive effort?</p>