If this idea gets applied please also make sure that the order of the RadPane(s) is retained when pinned or unpinned. For example, if a RadPaneGroup has three pinned RadPanes (B, A, C)...when this whole group becomes unpinned the order of the RadPanes when unpinned from top to bottom should be B, A, C. Also when mousing-over a RadPane, lets say pane A, pane A opens (unpinned), and then when the user click the pin button to pin pane A then pane A should be the active pane in the group. Again just like the Visual Studio docking environment.
This is the default behavior of the docking environment in an application like Visual Studio. I think that the Telerik RadDocking control should have this behavior as its default or have the ability to enable this behavior.