You can use the built-in editors to edit objects of many types available in EDT. However, almost all subordinate objects (such as attributes or commands) do not have editors. To edit such objects, use the Properties view. A notable exception is a form object, it has an editor.
Most of the editors contain several tabs. The list of tabs available in an editor depends on the object type. Some editors (for example, the All Roles editor) do not contain any tabs.