新建文件时，文本域为空，打开文件和保存文件时要给出输入对话框，输入相应文件名后进行操作，选择退出菜单将退出整个程序。
对文本域中选中的字符能够进行复制和粘贴操作。(When the new file is created, the text field is empty. When you open the file and save the file, you need to give the input dialog box, enter the corresponding file name, and then select the Exit menu to quit the whole program.
You can copy and paste the characters selected in the text field.)