Yes, it is possible to style RadPaneGroup like this. I have attached a sample that roughly resembles your design just to illustrate where the changes are to be made. I suggest you use the Metro theme as a base for your customizations.
Styling the appearance is simple. You need to customize the PaneHeaderStyle to add and align elements to the blue header of the RadPaneGroup. Furthermore, customize the control template of RadPaneGroup to show hide needed pin / unpin / close buttons, to add a separate grid row to give the folded paper effect of the pane header and so on.
The only thing that is not clear is the direction of the slide. If the desired effect is more like the expand / collapse effect, then I suggest you consider using the RadPanelBar control
I hope this helps.
the Telerik team
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