Create Hidden Sub-Menus
To create a sub-menu, create an additional «stereotype» element in the same toolbox profile and give it an attribute named "isHidden" with Initial Value of "true". Define the toolbox item attributes as before. In the parent «stereotype» element, create an attribute with the identical name to the sub-menu element. The sub-menu element can have an alias.
This technique is very useful for 'disambiguating' stereotypes that can be applied to multiple metaclasses. In the example below, the «MyStereo» stereotype can be applied to either a Class or an Interface. On dragging and dropping one from the toolbox, a hidden menu displays giving the choice of Class or Interface, then the appropriate element is dropped: