A CDockablePane cannot be undocked using drag-n-drop when the mouse buttons are swapped.
There is a bug in the CDockablePane::OnMouseMove handler where GetAsyncKeyState(VK_LBUTTON) is used without checking the swap state... using GetSystemMetrics(SM_SWAPBUTTON).
A partial workaround is to handle the OnMouseMove in your CDockablePane derived class. This workaround will not work if the dockable pane is docked as part of a tabbed pane.
A quick search also shows other places in the Feature Pack code where GetAsyncKeyState using VK_LBUTTON is called.