How are you calling the makeRectangle method? Are you calling it from paintComponent? What's GC? Is it some sort of Graphics object? How did you write your PaintListener class?
Last time I had that exercise I created a Shape interface
and a Rectangle class which implemented that interface and I put the object into a List and drew all the elements in that List in the paintComponent method. Of course, there is a Graphics object implicitly passed to the paintComponent method, ready for you to use. What about calling repaint() on the display from your mouse listener methods?
Please note the
code button makes your posts look much better. I have edited your post, since you are new, to show it to full effect.