title: How to change a WPF window backgroud with a data trigger?
body: <p>I want to change the background color of our apps main window when a property changes.  We have a business date that can be changed and I want to change the window background when it has changed from expected.  I've set up a property to tell this.  But can I set a style datatrigger on a window that changes itself?  Or would I need to do this in the app.xaml?  </p>