You want a class library, which is consumed by an app, to access variables in the app ? The best you can do is define delegates which can call back into the main app if they want to change the variable, and keep a local variable which your windows app can set. Actually, if it's a class, passing it through from the windows app should maintain a reference, which means changes will be reflected in the windows app. It depends, what exactly are you trying to do ?
Christian Graus - Microsoft MVP - C++ Metal Musings - Rex and my new metal blog