A document viewer control that is hosted by another computer program to provide that program with document viewing functionality, including enabling user interaction with the content. An interface provides the program with plug-in access to document viewing functionality, including scrolling, zooming, finding, layout, copying and the like. Properties may be retrieved and set via the interface, and commands may be issued. The result is that any program can provide document viewing functionality in a consistent manner. Moreover, via styles or the like, a program developer can deactivate and/or override default functionality, to customize and/or extend the document viewer as desired for a given program.