In JDK 1.3.1, the SystemMenu of JInternalFrame which is created by BasicInternalFrameTitlePane is hard-coded. So there is no way to do any Localization for them. We want to change the hard-coded English to Chinese.

In BasicInternalFrameTitlePane.java, you can see:
    protected static final String CLOSE_CMD = "Close";
    protected static final String ICONIFY_CMD = "Minimize";
    protected static final String RESTORE_CMD = "Restore";
    protected static final String MAXIMIZE_CMD = "Maximize";
    protected static final String MOVE_CMD = "Move";
    protected static final String SIZE_CMD = "Size";

However, from the JDK 1.4.0-Beta-02, these are changed to get the Texts from the UImanager as below:
    protected static final String CLOSE_CMD =
        UIManager.getString("InternalFrameTitlePane.closeButtonText");
    protected static final String ICONIFY_CMD =
        UIManager.getString("InternalFrameTitlePane.minimizeButtonText");
    protected static final String RESTORE_CMD =
        UIManager.getString("InternalFrameTitlePane.restoreButtonText");
    protected static final String MAXIMIZE_CMD =
        UIManager.getString("InternalFrameTitlePane.maximizeButtonText");
    protected static final String MOVE_CMD =
        UIManager.getString("InternalFrameTitlePane.moveButtonText");
    protected static final String SIZE_CMD =
        UIManager.getString("InternalFrameTitlePane.sizeButtonText");

Could you simply back port them from 1.4 to 1.3?