Property type 

treatment 

Simple  

Numeric, character, and string properties appear as numbers, characters, and strings. The application developer can edit the value of the property directly.  

Enumerated  

Properties of enumerated types (including Boolean) appear as editable strings. The developer can also cycle through the possible values by double-clicking the value column, and there is a drop-down list that shows all possible values.  

Set  

Properties of set types appear as sets. By double-clicking on the property, the developer can expand the set and treat each element as a Boolean value (true if it is included in the set).  

Object  

Properties that are themselves classes often have their own property editors, specified in the component's registration procedure. If the class held by a property has its own published properties, the Object Inspector lets the developer to expand the list (by double-clicking) to include these properties and edit them individually. Object properties must descend from TPersistent.  

Interface  

Properties that are interfaces can appear in the Object Inspector as long as the value is an interface that is implemented by a component (a descendant of TComponent). Interface properties often have their own property editors.  

Array  

Array properties must have their own property editors; the Object Inspector has no built-in support for editing them. You can specify a property editor when you register your components.