Wpf Tool Window Style Application not visible in alt+tab

I have a WPF application with

1. Main Window which is not a tool window
2. Launch a child window which has WindowStyle="ToolWindow" ShowInTaskbar="False" from main window

Now BOTH Main Window and Child Window are not visible in Alt+Tab. [Child window not appearing in alt+tab is expected behavior,but Main window should be visible]

Any help would be appreciated. Related link:http://social.msdn.microsoft.com/Forums/e开发者_如何学Gon-US/wpf/thread/95e076a3-3030-4dc0-ab23-a7e489b2a160

It works as expected on my machine (Windows 7) when using Show:

Window child = new Window();
child.Owner = this;

child.WindowStyle = WindowStyle.ToolWindow;

child.ShowInTaskbar = false;
child.Show();

When using ShowDialog, the issue occurs. However, I am wondering whether it makes sense to show a ToolWindow as Dialog - Tool Windows are usually no dialogs.