Question

I have got the the active window of a UI thread with GetActiveWindow. I need to close the window if it is a WPF pop up window.

How can I determine whether the window is a wpf window or not?

Answer 1

Use HwndSource.

http://msdn.microsoft.com/en-us/library/system.windows.interop.hwndsource.fromhwnd.aspx

As follows:

IntPtr hwnd = GetActivewWindow();

HwndSource hwndsrc = HwndSource.FromHwnd(hwnd);

// Use any variation on this code

if (hwndsrc != null && hwndsrc.RootVisual != null)
{
    Window window = hwndsrc.RootVisual as Window;

    if (window != null)
    {
        window.Close();
    }

    // UPDATE: I've added looking for a "Popup" window as well
    // because your question mentions "pop up window"...but
    // not sure if you meant a top-level Window, or a Popup...
    // ....Popup windows have HWND too!

    Popup popupwindow = hwndsrc.RootVisual as Popup;

    if (popupwindow != null)
    {
        popupwindow.IsOpen = false;
    }
}