All of the UML diagram elements share common context menu commands. To use the context menu for an element, simply right click on the element on the Diagram view. To view the common context menu commands, see Common Element Context Commands.
The object element offers the following additional context menu selections:
The object element has a special context command named, New, with a submenu for creating a new class or interface:

Class
Selecting New > Class from the context menu displays the New Object's Class dialog allowing you to create a new class:
Interface
Selecting New > Interface from the context menu displays the New Object's Interface dialog allowing you to create a new interface:
The object element also offers special context commands named Select Class and Unlink Class.
Select Class expands to display a submenu that shows any classes that are "local" to the diagram and an option named, More, for browsing available classes that you wish to associate with the object.
Local Class List (Class1, Class2)
If there are classes that are "local" to the diagram, then they will display in this list. Select the class from the list to associate it with the object.
More
Select More to open a file browsing dialog to select a class to associate with an object.
Once a class or interface has been associated with an object, the Show Class command is enabled. This command offers special context commands named, In Editor, In Resource Navigator, In Package Explorer, and In Model Navigator.

In Editor
Opens the source file in the Editor window.
In Navigator
Opens the Navigator view, navigates to and highlights the source file in the view.
In Package Explorer
Opens the Package Explorer view, navigates to and highlights the source file in the view.
In UML Navigator
Opens the UML Navigator view, navigates to and highlights the source file in the view.
Use Unlink Class to unlink a previously linked class or interface from an object.