Embedded on the LitCrit form is a Visual Basic element similar to an ActiveX control. (For information on using such an element in an Outlook form, see Creating the Microsoft Outlook Form.) This element was created using Microsoft Visual Basic within an "ActiveX DLL" project. ActiveX DLLs are distinguished from ActiveX controls in that controls have their own user interface (technically, an ActiveX control is a blank area of screen on which you can overlay other controls), whereas ActiveX DLLs such as this one in the CML/LitCrit project have no initial user interface of their own.
At design time in Visual Basic, the LitCritC ActiveX DLL project is displayed as a gray rectangle similar to a standard Visual Basic form but without a form border. It differs in other ways as well: You cannot at design time place user interface elements such as text fields and buttons on this ActiveX DLL project. And at run time, because it is not an ActiveX control, it occupies no screen area. But an ActiveX DLL can host other elements at run time, such as controls. In the case of CML/LitCrit, it displays the Choose Title dialog box.
This functionality, provided by the technologies of Microsoft Outlook and ActiveX, occurs on the client's computer, and the objects instantiated in this section reside in client computer memory. While the user interface of this functionality is on the user-services tier, the underlying logic is on the business layer: Not only does it communicate with both adjacent tiers (data-services and user-services), it represents the business logic of the CML/LitCrit application.
For information about the functionality of this dialog box, see Using the Find Library Title Dialog Box and About the ChooseTitle Method.