Current Solution :

  1. Two manage AppDomain hosted in one native Process. So when one exception managed pop-up dialog is shown in one application, in the major native process we need to force to bring the it to front.
  2. In case you try to monitor the Windows Message flow beside override WndProc() method. Another alternative is Message Filter for Application API. IMessageFilter Interface and How-to add Filter for WPF– MSDN API
  3. In case, you try to bring the ModalDialog to backend, as the most relevant application may be switched to lose focus. Just setParent() and set TopMost=false, see “backend ShowDialog”