Debug a WPF window or Windows Form without running your application?

Debug a WPF window or Windows Form without running your application?

I'm new to WPF and have a question which quite same with the article:
"Walkthrough: Debug a WPF window or Windows Form without running your
application".
The link:
http://blogs.msdn.com/b/habibh/archive/2009/07/17/walkthrough-debug-a-wpf-window-or-windows-form-without-running-your-application-video.aspx
I will take the picture as an example:
http://blogs.msdn.com/blogfiles/habibh/WindowsLiveWriter/DebugaWPFwindoworWindowsFormwithoutrunni_FD38/image_3.png
From the picture, the project have 4 WPF windows such as:
App.xaml
Create...so on.xaml
MainWindows.xaml
ViewChart... so on.xaml
When every time in VS 2010, I click on the starting debugging (F5) or
start without debugging(Ctrl + F5) will always run the MainWindows.xaml.
What the reason coz this? Is this because of in the App.xaml that we
declare StartupUri="MainWindow.xaml".
Can I run the particular WPF windows such number 4. ViewChart... so
on.xaml instead of the whole application(*Such as the MainWindows.xaml)?