Thank you for contacting us.
The concept for RadRibbonBar is basically to have one RadRibbonBar that contains all the possible functionalities for the application (just like in Microsoft Office). This is why we do not support ribbons in MDI children. The architecture and features of our RadRibbonBar is based on the Microsoft's guidelines for RibbonBars.
I hope you find this information helpful. Should you need any other assistance, do not hesitate to contact us.
the Telerik team