private ToolButton createButton(DrawingTool tool, String image, JPanel propertiesPanel) {
   ToolButton button =
       new ToolButton(
           new ImageIcon(
               Toolkit.getDefaultToolkit().getImage(getClass().getResource("/" + image))),
           tool,
           propertiesPanel);
   button.addActionListener(buttonHandler);
   button.setPreferredSize(new Dimension(30, 30));
   buttonList.add(button);
   return button;
 }