added openCV.h to each class

example/main.cpp

@@ -13,8 +13,7 @@ int main() {
     bool fullscreen;
     
     fullscreen = true; 
-    
-    fullscreen = false;
+    //fullscreen = false;
     
     cout << "> display configuration" << endl;
     cout << "* fullscreen: " << (fullscreen ? "yes" : "no") << endl;