the logo example shows a very nice way to add new items with this right-click and then rotating throw the available parts.
But probably not the best way if you think about a application like UML or dialog editors, where you can have lots of items in your toolbox. In Gef 3.x there was support for a palette.
Is there a palette in GEF4 MVC?
Up to now, there is no direct support for a palette in GEF4 MVC. The intended way is to use a second viewer that renders the palette items (and thus is not restricted to using buttons and icons), realizing a prototype-based creation through drag-and-drop.