Sometimes you want the window handle of the host application when you're writing an Office add-in. Excel includes that as a property of the Application object in newer versions of the object model, but Word and PowerPoint don't. I seem to remember some sample code from Microsoft that suggests using FindWindow to get the handle, but that always seems problematic:
Instead, if you're using managed code, you can just do this:
IntPtr hwnd = Process.GetCurrentProcess().MainWindowHandle;
Underneath this uses
find the right window.