public FeedManager(){

        loadListbox();  

        this.setPreferredSize(new Dimension(500,255));
        this.setResizable(false);
        this.setSize(500, 500);

        ActionListener action = (ActionEvent e) -> {
            if(null != e.getActionCommand()){
                switch (e.getActionCommand()) {
                case "OK":
                    this.dispose();
                    break;
                case "AddFeed":                   
                    addFeed();
                    txtFeedURL.setText("");
                    break;
                case "Delete":
                    removeFromList(this.listFeed.getSelectedValue().toString());
                    break;
                }
            }
        };

        this.btnOK.setActionCommand("OK");
        this.btnOK.addActionListener(action);
        
        this.btnAdd.setActionCommand("AddFeed");
        this.btnAdd.addActionListener(action);
                
        this.btnDelete.setActionCommand("Delete");
        this.btnDelete.addActionListener(action);
  
        this.contentFirstRow.setLayout(new BoxLayout(this.contentFirstRow, BoxLayout.LINE_AXIS));
        
        this.contentFirstRow.add(Box.createHorizontalGlue());
        this.contentFirstRow.add(Box.createRigidArea(new Dimension(5, 0)));
        this.contentFirstRow.add(this.lblFeedURL);
        this.contentFirstRow.add(Box.createRigidArea(new Dimension(5, 0)));
        this.contentFirstRow.add(this.txtFeedURL);
        this.contentFirstRow.add(Box.createRigidArea(new Dimension(5, 0)));
        this.contentFirstRow.add(this.btnAdd);
        
        this.contentButtons.setLayout(new BoxLayout(this.contentButtons, BoxLayout.LINE_AXIS));
        this.contentButtons.add(this.btnOK);
        this.contentButtons.add(Box.createRigidArea(new Dimension(5, 0)));
        this.contentButtons.add(this.btnDelete);

        buildLayout();                  
    }