Netsilon features a UML class diagram editor.
To move elements, just drag and drop them in the diagram. To resize an element, select it by clicking on it and use the bold dots that appears (BM_User_Access in the above example). You can break bounds by selecting them and dropping elsewhere (as done for the link readers / contribution_read in the above example). Deleting an element (del key) will remove it from the project; if an element exists on more than one diagram, it will be asked if only the selected figure should be remove, or everyone. Deleting a class will delete all of its inheritance and associations. You can invoke popup menus by right-clicking on an element.
The toolbar provides the following items:
(Select)
et 
(Broom)
show the selection mode.
(Package)
creates a new package (at the location designated by the pointer).
(ClassDiagram)
creates a new class diagram.
(Class)
creates a new class.
(Association)
creates an association (right-click on the source and release on the target
class).
(Generalization)
creates an inheritance relation (right-click on the child and release on the
parent class).
(AssociationClass)
creates an association-class (right-click on the first and release on the
second class).
(Add
Attribute) adds an attribute to the selected class.
(Add
Operation) adds an operation to the selected class.
The bodies of the methods (accessible by double-clicking on the method in the browser, or using the operation or method popup menu) are defined using the action language Xion.