Swing/AWT/SWT :: Calling Method Does Not Work From JMenuBar

I have a paint program in Java where I can draw objects. The objects are stored in an arrayList. In the menubar the user can chooce "Back", which means the last item in the arrayList is removed. After that I want the program to loop through the arrayList and draw the remaining items.

My problem is that when I try to do that it will not work from the menu (menuItem2). If I instead add the code to one of the colorpanels (yellowPanel), from where the user can pick colors, it works fine.

menuItem2 uses ActionListener and yellowPanel uses MouseListener.
public class PaintProgram extends JFrame implements ActionListener {

public ArrayList<Draw> shapeList = new ArrayList<>();
int startX, startY, endX, endY, w, h;
private JPanel topPanel;
private JPanel bottomPanel;
private JPanel magentaPanel;
private JPanel greenPanel;
private JPanel bluePanel;
private JPanel blackPanel;

[code]....