Request: toolbar/headerbar component

It's entirely possible that I overlooked this, but I haven't seen a toolbar component. It would be wonderful if such a component could be added. As a bonus, it would be great if toolbars could be horizontal and vertical, but I'm not sure if this is supported on all platforms.

The developers are to be congratulated on the remarkable amount that you've achieved with this project thus far. It is an exciting time for desktop application developers. Thank you.