You can style RadDocking
exactly as it is shown in the attached screenshot. I suggest you using Implicit styles
theme mechanism for styling RadDocking
For that purpose you need to take the RadDocking resources from the installation folder on you machine. Inside that folder you will find the Themes.Implicit folder which contains all themes resources. RadDocking is inside the Telerik.Windows.Controls.Docking.xaml file which contains all needed styles and resources.
I've demonstrated a sample demo in the attached project using Windows8Touch theme. Please note the project shows only how to customiza the RadDocumentPane, in order to have the same style for other RadPanes you need to modify the corresponding control template of RadPane style.
I hope it helps.
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