The Orbit

This is a picture of Orbit in its default configuration:


All the icons shown are items. By left-clicking one of them, the configured action is performed. By right-clicking one of them, a context menu appears showing the actions that can be done with that item. By default, the icon with the cogwheel is the configuration item.
Spinning the mouse wheel performs various actions depending on the context of the open loop. it either spins the loop or scrolls to show occluded items.