Thanks for your interest in our Silverlight controls.
I have created a project with the templates that you will need to add buttons in the RadPaneGroup's
header. Currently the only way to do it is through templates. I don't know how exactly you intend to use the buttons. If they are going to be dynamic you may have to extend some classes and add functionality to manage the buttons. The dock creates new pane groups when you drag things around so if you drag the panel now you will lose the buttons. If you need them on all groups you may have to create a custom theme and set the default dock templates with custom ones.
We have additional resources that may help you:
the Telerik team