Icon icon = UIManager.getIcon("InternalFrame.closeIcon"); if (icon != null) closeButton.setIcon(icon); icon = UIManager.getIcon("InternalFrame.iconifyIcon"); if (icon != null) iconButton.setIcon(icon); icon = UIManager.getIcon("InternalFrame.maximizeIcon"); if (icon != null) maxButton.setIcon(icon);
if (closeIcon != null) closeButton.setIcon(closeIcon); if (iconIcon != null) iconButton.setIcon(iconIcon); if (maxIcon != null) maxButton.setIcon(maxIcon);
  protected void setButtonIcons()  {    Icon icon = UIManager.getIcon("InternalFrame.closeIcon");    if (icon != null)      closeButton.setIcon(icon);    icon = UIManager.getIcon("InternalFrame.iconifyIcon");    if (icon != null)      iconButton.setIcon(icon);    icon = UIManager.getIcon("InternalFrame.maximizeIcon");    if (icon != null)      maxButton.setIcon(icon);  }