7 Trong đoạn mã dưới đây, lớp myButton một lớp bên trong của TrackEvent, vì vậy myButton có thể đạt được vào cửa sổ cha mẹ và thao tác các lĩnh vực văn bản của nó, đó là cần thiết để viết các thông tin trạng thái vào các lĩnh vực của phụ huynh. Tất nhiên, đây là một | A user interface is well designed when the program model conforms to the user model. That s it. Almost all good user interface design comes down to bringing the program model and the user model in line. The Macintosh UI would have been more successful especially for my poor friend if it saved your unsaved work for you. Of course in 1985 the slow speed of floppy disks made this impractical. But in 1988 by which time everybody had hard drives this became inexcusable. To this day most popular software doesn t automatically save your work. Let s look at another example. In Microsoft Word and most word processors when you put a picture in your document the picture is actually embedded in the same file as the document itself. You can create the picture drag it into the document then delete the original picture file but the picture will still remain in the document. Now HTML doesn t let you do this. HTML documents must store their pictures in a separate file. If you take a user who is used to word processors and doesn t know anything about HTML then sit them down in front of a nice WYSIWYG HTML editor like Microsoft FrontPage they will almost certainly think that the picture is going to be stored in the file. Call this user model inertia if you will. So we have an unhappy conflict of user model the picture will be embedded versus program model the picture must be in a separate file and the UI is bound to cause problems. If you re designing a program like FrontPage you ve just found your first UI problem. You can t really change HTML after all it s an international standard. Something has to give to bring the program model in line with the user model. You have a couple of choices. You can try to change the user model. This turns out to be remarkably hard. You could explain things in the manual but everybody knows that users don t read manuals and they probably shouldn t have to. Or you can pop up a little dialog box explaining that the image file won t be embedded but this
