Correct cursor problem in C++ source code

This is a minor task to do in C++ Version 6. Attention: I'm not allowed to give the whole source to someone. A solution could be to do the work in here, via skype, teamviewer or alike. The project itself is an ActiveX control. It provides an OpenGL window and has a lot of sophisticated functionality. It complies with no errors, and it runs well - since years. The nature of the problem to be solved is trivial. It has nothing to do with the OpenGL and other stuff. It is about the cursor handling. From the container side I can set a cursor to show, and this works well. There is a property to set the cursor for the control (SetCustomCursor). It uses SetClassLong(m_hWnd, GCL_HCURSOR, (LONG) nNewValue);. And exactly this is the problem, as it sets the cursor for the whole class. Means, every instance of the control uses the same cursor then. This is not wanted, it must be possible to set the cursor different for every instance of the control. So correct way is to write an own handler to WM_SETCURSOR message in windows message handling routine. This is what needs to be done. There is also another cursor system in the control, which reacts on different mouse actions. This one simply uses SetCursor and works as expected. The cursor data is in the control itself as a ressource. This system may not be touched or altered.