Special Considerations for ActiveX Control Development

Your custom control will be used by other developers who will in turn employ it in their own programs for their own end users. This fact complicates custom control creation in several major areas:

• You must manage property values so that they persist from the developer's design-time changes to the runtime environment.

• You must allow for the interaction between the members of your control, its constituent controls, and both the design-time and runtime environment in which the developer has placed your control.

• You must ensure that your control cannot be used maliciously by developers.

• You must decide whether your control can be used only by licensed developers and, if so, you must implement a licensing scheme.

We discuss the first two points in the section that follows titled "Steps to Creating an ActiveX Control that Expose Properties." We discuss control security, distribution, and licensing in the sections at the end of this chapter.