Oh well, if you edit your post, I'll edit mine.
You still have this in class Screen
//friend class Rectangle;
This need to be uncommented, it doesn't do anything while commented out.
With this code in Rectangle:draw:
object.pixels[x1][y1]; // you said it does not make sense
What do you want this line to do? It is not assigning anything, and it is not testing anything. I assume you want something like:
object.pixels[x1][y1] = 'x';