Vs Toolbar for a split tool window

[pascalgyger]

Does anybody know how we can implement a VS Toolbar (as defined in the vsct file) for a split toolwindow? What we would like to achieve is a toolwindow with a left and right section and have a Toolbar shown only in the right section. It's similar to how the Git Manage Branches Toolwindow looks. They also show a Toolbar only in the right section.

Since the toolbar is registered on the ToolWindowPane is there somehow a way to have two ToolWindowPanes in the same ToolWindow?