I was trying to find the sample code and was unsuccessful, so tried to write it by my own.
Again the gradient brushes, control template applied to ListBoxItem, Dockpanels and the layout system amazed me. It's so fun to develop user interfaces on top of hidden technologies! I'm getting used to it.
*Note: There's a sample on gotdotnet, check it too. It's also a personal try of the sample.