Rewrite your Matrices and Vectors program to incorporate an event-driven user interface. Use the files event.h and event.cpp as the basis for your event-driven API. Construct whatever objects you deem necessary to make the interface usable (eg. dialog boxes, controls, input boxes, etc.).
You may make changes to the basic files if you feel that by doing so you will improve the capabilities of the system. Unless absolutely necessary, most such changes can be incorporated by simply deriving new classes.
Define windows that are capable of inputting a vector/matrix as well as windows that are capable of displaying a vector/matrix. Assume a fixed number of vectors/matrices and put in menus to perform operations on these vectors/matrices. The menu handlers must use the overloaded operators from the previous practical.
Test your GUI thoroughly using all combinations of test data and menu selections.