public void actionPerformed(ActionEvent event) { if (scene.canRemove()) // If shapes can be removed { scene.removeSelected(); // if no more objects can be removed, disable this action if (!scene.canRemove()) { setEnabled(false); } // check if the opposites can be enabled. checkOpposite(); } else { // disable this action, check if opposites can be enabled setEnabled(false); checkOpposite(); } }