John, if you want to know just read his post. It's very simple to read and very simple to understand (or do not make this kind of answer). This is a very specific problem and google will not help. And abhinav the WindowsFormsIntegration.dll cannot help you for your problem. Just try to listen Application.Current.Activated and Deactivated event to change the TopMost value of the form. I guess it can be a good beginning...

Need help ? Ask me :)